We evaluated the effects of long-term feeding of a fishmeal-free (FMF) diet on the growth parameters and physiological status, especially the bile acid status, of red sea bream (Pagrus major) yearlings. Two isonitrogenous and isolipidic diets were prepared; a fishmeal-based diet as the control, and an FMF diet containing soybean meal, corn gluten meal, soy protein concentrate, and pea protein concentrate as plant-derived ingredients, and poultry by-product meal and feather meal as animal-derived ingredients. Six hundred red sea bream yearlings were accommodated in six net cages, and the two experimental diets were hand-fed for 36 weeks. Throughout the 36-week trial, mean body weight and feed intake were significantly lower in the FMF group than in the control group. The concentrations of serum total cholesterol and high-density lipoprotein cholesterol were also significantly lower in the FMF group than in the control group throughout the trial. The total bile acid amount per fish was significantly lower in the FMF group than in the control group between Week 32 and 36 when the water temperature was the lowest (14.3–17.2 °C). Gene expression levels of hepatic cyp7a1 and cyp8b1 tended to be lower in the FMF group than in the control group from Week 20 to the end of the trial. Expression levels of hepatic sqle were higher in the FMF group than in the control group through the trial period and were markedly high at Week 36. Expression of hmgcr was also higher in the FMF group than in the control group at Week 32 and 36. The hindgut asbt expression of fish fed the FMF diet was lower than those fed the control diet at Week 28 and 32. These results suggest that the long-term feeding of an FMF diet to red sea bream yearlings causes reduced growth due to a significant reduction in feed intake and bile acid production, and enterohepatic circulation are strongly disturbed when water temperatures are low from autumn to winter.

Three experiments were performed to explore (i) the complete replacement of fish meal (FM) with a combination of fish residue meal (FRM, 65% round discarded fish + 35% byproduct), soy protein concentrate (SPC) from soymilk and corn gluten meal (CGM) in Trial 1 and (ii) the utilization of diets composed of increasing byproducts in FRM in the summer (Trial 2) and winter (Trial 3) seasons. In Trial 1, the ratio of (SPC + CGM):FM in the control diet (C) was 8:2. The FM component from diet C was replaced with FRM (diet, RM20), where the ratio of (SPC + CGM):FRM became 8:2, and this ratio was changed to 6:4, 4:6 and 2:8, and referred to as RM40, RM60 and RM80, respectively. In Trials 2 and 3, the ratios of round discarded fish and byproducts in FRM were adjusted to 65:35 (FRM1), 30:70 (FRM2) and 0:100 (FRM3), and the FRM component from diet RM40 in Trial 1 was replaced with FRM1, FRM2 and FRM3 to formulate diets RM1, RM2 and RM3, respectively. In Trials 1, 2 and 3, rearing periods were 10, 8 and 12 weeks, respectively. In Trials 1 and 3, there were no significant differences in growth parameters, nutrient retention efficiency or plasma constituents among the treatments, irrespective of the inclusion levels of FRM in the diets (p > 0.05). Although there were no significant differences in final mean weight (p > 0.05), daily feeding rate and feed conversion ratio in diet RM3 were significantly higher and lower, respectively, compared to the control group in Trial 2 (p < 0.05). These results suggest that FM can be entirely replaced with FRM, and that the total elimination of round discarded fish from FRM does not affect growth or health status in red sea bream either in summer or winter seasons.

We replaced fish meal (FM) with porcine blood meal (BM) in red sea bream (Pagrus major) diets to examine the influence on growth performance. Four experimental diets were prepared to be isonitrogenous and isolipidic by replacing 0%, 10%, 20% and 30% FM protein with BM (BM0, BM10, BM20 and BM30, respectively). After the 8-week feeding trial, the final mean body weight, weight gain, specific growth rate, daily feeding rate, condition factor and survival rate were not significantly different among the treatments (p > 0.05). However, feed efficiency tended to lower linearly as the dietary BM level increased, and no significant difference was observed between the BM20 and BM0 groups (p < 0.05). The protein digestibility in the BM20 and BM30 groups decreased significantly compared with that in the BM0 group (p < 0.05). Fat digestibility decreased significantly in the BM30 group than in other treatment groups (p < 0.05). The total serum protein and total cholesterol concentrations in the BM30 group were the highest among all treatment groups. In conclusion, BM can replace up to 20% of FM in the red sea bream diet without adversely affecting growth performance.

Potato protein concentrate (PPC) is a potential fish meal (FM) substitute. We replaced FM in greater amberjack diets with low-temperature air-dried PPC (LT-PPC) and high-temperature rotary-dried PPC (HT-PPC) to investigate their effects on growth and feed utilization. Four experimental and one control diet was prepared. The control diet comprised FM, wherein the experimental diets were prepared by replacing 20 and 40% of FM in the control diet with LT-PPC (LP20 and LP40) or HT-PPC (LP20 and LP40). Following an 8-week growth trial, the final mean body weight, specific growth rate, and feed intake of HP40 diet-fed fish were significantly lower than those of control diet-fed fish (p < 0.05). However, these parameters in LT-PPC and HP20 diet-fed fish did not differ significantly from those of the control diet-fed fish (p> 0.05). In vitro relative protein digestibility did not differ between LT-PPC (91.1%) and HT-PPC (89.5%) (p > 0.05); however, the digestion speed of LT-PPC was higher (63.8%) than that of HT-PPC (46.8%) (p < 0.05). In conclusion, the findings demonstrate that LT-PPC and HT-PPC could be used to replace up to 40 and 20% of FM in greater amberjack diets, respectively, without compromising growth performance.

Changes in nutritional constituents and enzyme activities were clarified in yellowfin tuna (YFT, Thunnus albacares) eggs during embryonic development, from eggs immediately after fertilization to hatching. The protein levels in the eggs gradually increased with development until the completion of hatching. In contrast, the triglyceride (TG) and free amino acid (FAA) levels in the eggs gradually declined with embryonic development until hatching was complete, although the energy composition of the FAAs was lower than that of the TGs throughout embryonic development. These results indicate that endogenous TGs are preferentially expended as an energy source during embryonic development. Overall, changes in the activities of aspartate aminotransferase, alanine aminotransferase, creatine kinase, and alkaline phosphatase showed similar patterns throughout development. First, the enzyme levels diminished; then, they remained at constant, low levels just before hatching, when they rapidly increased. This rapid increase was consistent with the protein content, suggesting that organ differentiation and functionalization were promoted during this period. These results will contribute to the establishment of mass-seeding production of YFT.

Fish meal (FM) used in fish farming is prepared by steaming, squeezing, defatting, drying and crushing raw fish material. However, how drying affects protein digestibility has not been systematically studied. Herein, we evaluate the effect of additional heating of FM on in vitro FM protein digestibility and growth performance of white trevally (Pseudocaranx dentex) juveniles. We heated conventional steam-dried Chilean FM from 50-200 degrees C for 1 h to prepare additionally heated FM (AHFM). In-vitro AHFM protein digestibility started to decrease significantly above 150 degrees C, along with substantial reduction in the protein digestion speed. Five isonitrogenous/isolipidic experimental diets were prepared by substituting different proportions of FM with AHFM produced by heating FM to 180 degrees C. In-vitro protein digestibility and digestion speed of the experimental diets decreased linearly with increasing AHFM content. After a 33-d feeding trial, the final bodyweight, specific growth rate, weight gain and feed efficiency of white trevallies decreased linearly and/or quadratically with increasing dietary AHFM levels. These findings indicate that in vitro protein digestibility of AHFM decreases linearly at temperatures above 150 degrees C, and the growth and feed efficiency of white trevallies are negatively affected by dietary inclusion of AHFM processed at 180 degrees C.

Black soldier fly meal (BM) is an outstanding candidate as a fish meal (FM) substitute because it contains relatively high protein and essential amino acids. In this study, we replaced FM in red sea bream diets (Pagrus major) with BM to investigate its effect on growth and feed utilization. Six isonitrogenous and isolipidic experimental diets were prepared by substituting 0%, 20%, 40%, 60%, 80% and 100% FM protein with BM (Control, BM20, BM40, BM60, BM80 and BM100, respectively). After the 8-week feeding trial, final body weight, weight gain, specific growth rate and feed efficiency decreased linearly with increasing dietary BM level (p < 0.05). Apparent digestibility of protein and fat and serum total cholesterol concentration decreased with increasing dietary BM levels (p < 0.05) Final body weight, WG, SGR and FE against dietary BM level had breaking points of 76.2%, 41.7%, 76.5% and 60.0%, respectively, in segmental regression analysis. In conclusion, the results suggest that BM can replace a maximum of 41.7% of FM in the diet of red sea bream without compromising growth performance or feed efficiency for 56 days.

The optimum level of fishmeal (FM) protein replacement by bacterial protein meal (BPM) was determined in the diet of juvenile red sea bream, Pagrus major. Six isoproteic and isolipidic diets were formulated to replace 0 (control diet), 190, 280, 370, 470 and 560 g of the FM protein kg-1 diet with BPM protein, and referred to as C, BP19, BP28, BP37, BP47 and BP56, respectively. Each diet was fed to triplicate groups of twenty fish (mean weight ~43 g) twice per day to apparent satiation. Fish fed diets C and BP19 did not show significant differences (p >.05) in growth, apparent digestibility or protein and lipid retention efficiency, but the daily feeding rate (DFR) was significantly lower under BP19 than under C. However, almost all growth parameters were significantly reduced when FM protein replacement with BPM was further increased from 280 to 560 g kg-1 diet (p <.05). The results of polynomial regression analysis (second-order) revealed significant negative correlations between dietary copper levels and final mean weight (R2 =.913), specific growth rate (R2 =.913) and DFR (R2 =.956). The results indicated that BPM could replace approximately 190 g of FM protein kg-1 diet in the juvenile red sea bream diet without compromising growth performance or feed efficiency.

© 2019 John Wiley & Sons Ltd Potato protein concentrate (PPC) is a promising candidate as a fish meal (FM) substitute because it has high protein and essential amino acid content. In the present study, we replaced FM in greater amberjack diets with PPC to investigate the effect on growth and feed utilization. Four isonitrogenous, isolipidic and isocaloric experimental diets were prepared by substituting 0, 20, 40 and 60% of FM protein with PPC (Control, P20, P40 and P60 respectively). The in vitro protein digestibility of protein in PPC was 88.8%, relative to 100% protein in the FM. The in vitro protein digestibility of protein in the experimental diets also decreased with increasing PPC and was lowest at 84.2% in P60. After the 7-week feeding trial, final body weight, weight gain and thermal growth coefficient tended to decrease with increasing PPC and were significantly lower in P60 than in the control (p <.05). Further, fish fed with diets P40 and P60 showed significantly lower feed conversion and protein efficiency ratios than the control group (p <.05). In conclusion, the results suggest that PPC can replace up to 20% of FM in the diet of greater amberjack without compromising the growth performance or feed efficiency.

In this study, we isolated and characterized the acid-soluble skin collagen of Pacific bluefin tuna (PBT, Thunnus orientalis). The PBT skin collagen was composed of two α chains (α1 and α2) and one β chain. The denaturation temperature of PBT collagen was low although it was rich in proline and hydroxyproline. The primary structure of PBT skin collagen was almost identical to that of calf and salmon skin collagen however, it differed with respect to the epitope recognition of the antibody against salmon type I collagen. These results suggest that the primary structure of skin collagen was highly conserved among animal species, although partial sequences that included the epitope structure differed among collagens.

© 2018 Japanese Society for Aquaculture Research, Nishimura Toushadou Ltd.. All rights reserved. A noninvasive assay for estimating stomach evacuation velocity and daily meal frequency for a commercially available artificial diet was evaluated using Pacific bluefin tuna fingerlings. This was attributed to the hypothesis that fish could consume a diet until filling up a gap of the stomach after a feeding until satiation. Consecutive feeding frequencies of 4, 11 and 3 meals daily from 7: 00 to 17: 00 for 5 days each, were conducted on a single group of 1,200 fingerlings, weighing 70-190 g in a net cage. The daily feed intake linearly increased with passing the feeding protocols. For each daily feeding event, ô daily feed intake of a first meal was higher than those of second meals onward in a day. The stomach evacuation velocity expressed as a slope, subtracting accumulative ô daily feed intake of a second meal onward from that of a first meal, was y =-6.94x + 29.6, y =-7.08x + 31.2 and y =-7.07x + 44.4 for 4, 11 and 3 meals daily, respectively. These results indicate that the stomach evacuation velocity of the fingerlings was estimated to be around 7ô daily feed intake per hour, and daily meal frequency was 3 or 4 until apparent satiety was achieved with the artificial diet.

Six isoenergetic diets were formulated as follows: fish meal (FM) 700gkg(-1) (control, C), FM 300gkg(-1) + soy protein concentrate 300gkg(-1) (SPC), FM 300gkg(-1) + enzyme-treated SPC 300gkg(-1) (ESC), FM 170gkg(-1) + soy protein isolate 300gkg(-1) (SPI), FM 160gkg(-1) + enzyme-treated SPI 300gkg(-1) (ESI) and FM 150gkg(-1) + conglycinin 300gkg(-1)(CG). Forty fish (3.9g) were randomly distributed into each of eighteen 300-L tanks, fed twice daily until satiation for 8weeks. The final body weight, specific growth rate and condition factor did not show significant differences among the fish fed with diets C, SPC, ESC and ESI (p>.05). The survival was significantly lower in fish fed with diets SPI and CG. Feed efficiency was significantly higher in fish fed with diets SPC and C than in fish fed with other diets (p<.05). There were no significant differences in nutrients retention efficiencies in fish fed with diets C, SPC, ESC and ESI. A significantly higher phosphorus retention efficiency in fish fed with soymilk protein diets resulted in lower phosphorus discharge to the environment (p<.05). These results suggest that the soymilk proteins can comfortably replace 570-770gFMkg(-1) diet of red sea bream juvenile, which will ensure significant ecological benefits through reducing phosphorus load to the environment.

To determine the optimal stocking density, three densities of 5 (SD5), 10 (SD10), and 15kg/m(3) (SD15) were used to culture striped knifejaw, Oplegnathus fasciatus, for 10 wk. A total of 10, 20, or 30 juveniles with mean weights of approximately 96g were stocked into one of nine 300-L tanks (with an initial water volume of 200L) and fed with commercial feed via self-feeders. The fish were sampled at 4 and 8 wk, and the stocking density was maintained by adjusting the water volume of the tanks. The final body weights in SD10 and SD15 were 183.8 and 178.9g, respectively, which were significantly higher than 161.7g in SD5 (P< 0.05). However, there was no significant difference between the SD10 and SD15 (P > 0.05). A similar trend was observed in the specific growth rate among the treatments. Feed efficiency and the lipid retention efficiency were both significantly higher in SD10 than that in SD5. The plasma levels of cortisol, glucose, and total protein were similar among the treatments. These results clearly suggest that densities of 10 and 15kg/m(3) can be used to improve the growth performance of striped knifejaw, O. fasciatus, when fed with a self-feeder.

Six light intensities (50, 100, 200, 400, 800, and 1500 lx) were used under a photoperiod of 16 h light : 8 h dark (16L : 8D) to investigate the growth performance and stress response of striped knifejaw, Oplegnathus fasciatus. Forty juveniles of mean weight approximately 27 g were randomly distributed into each of eighteen 300 L tanks, fed to apparent satiation two times a day for 8 wk. At the end of the rearing trial, there were no significant differences in final mean weight, weight gain, specific growth rate, condition factor, and survival among the treatments (P > 0.05). Although there was no significant difference in feed intake, fish exposed to 50-200 lx showed significantly higher feed efficiency (FE) compared to that of other treatments (P < 0.05). There was a decreasing trend in retention efficiency of protein and lipid with increasing light intensities (400-1500 lx), but there were no significant differences among the treatments. There were no significant differences in plasma levels of cortisol, glucose, and total protein among the treatments (P > 0.05). To consider the FE and given the fact that an intensity of 50 lx is insufficient to monitor fish activity during feeding, light intensity of 100-200 lx would be better for rearing of striped knifejaw.

The characteristics of dietary utilization, energy conversion efficiency, metabolic rate and energy partitioning were measured for cultured Pacific bluefin tuna (PBT) juveniles fed on an artificial diet. Thirty-one juveniles (1.1 +/- 0.3 g BW) were stocked into each of two 2500 L tanks to measure oxygen consumption ((M) over barO(2)), swimming speed, digestibility and growth performance. (M) over barO(2) elevated until 2.5 +/- 0.3 times of pre-feeding level within 1.5 h after feeding, except for the first feeding, and returned to pre-feeding level within 3 h. Swimming speed fluctuation was corresponded with the (M) over barO(2) fluctuation, and both parameters were stable from 02:00 to 06:00 and also during the whole day for starved fish. These indicate that feeding has strong influence on their metabolic rate. Energy partitioning for faecal, urinary and branchial, heat increment and voluntary activity, standard metabolism, and retained energy were calculated to be 17.2%, 5.9%, 14.9%, 41.3% and 20.7% of total ingested energy, respectively. The results indicate that, unlike other fish, juvenile PBT distribute large amount of energy for maintenance, which allows only a little proportion of ingested energy available for growth.

The energy partitioning in juvenile chub mackerel was assayed using the apparent digestibility, growth performance, oxygen consumption rate (a3/4O(2)), and swimming speed with feeding on an artificial diet. Fifty-four juveniles (16.6 g) were divided into two 2500 L tanks and reared for 2 weeks. The a3/4O(2) after the first, second, and the third feeding elevated 1.4, 1.9 and 1.9 fold higher than that of under fasting, and returned to the pre-feeding level within 4, 4, and 9 h, respectively. The post-feeding swimming speed fluctuation of juveniles was significantly correlated with their a3/4O(2) fluctuation. In contrast, although there was no remarkable change in a3/4O(2) under fasting for all day, their swimming velocity continued to decline slowly from sunset to sunrise. Energy partitioning rates for fecal, urinary and branchial, heat increment and voluntary activity, standard metabolism, and retained energy were calculated as 7.4, 8.7, 35.9, 23.5, and 24.5 % of total ingested energy, respectively. The results revealed that juvenile chub mackerel shifted respiratory strategy from ram-ventilation to branchial ventilation from sunset to sunrise. Moreover, chub mackerel juveniles, one of the typical carnivorous fish, distribute more energy for maintenance resulting in lower energy allocation for growth as compared with other aquaculture fishes.

The ship- and truck-transportations of Pacific bluefin tuna (PBF) fingerlings that place the last stage of their mass artificial production, repeatedly end in fruitless and uncomfortable performance. Technical advance of fingerling transportation would surely promote the aquaculture production of PBF in Japan. In the present study, changes in whole body and muscle proximate composition and fatty acid profile during ship-transportation were investigated to obtain basic knowledge for prompting its technical establishment. The PBF fingerlings with 27g body weight were transported from the net pen in the Kushimoto Bay to that in the Uragami Bay by a ship (14.4 mt), taking about 10 miles and 1.5 h. Water temperature and dissolved oxygen were respectively 21.2°C and 6.98 mg/L at the Kushimoto Bay and 21.7°C and 6.39 mg/L at the Uragami Bay. In whole body, no decreasing was detected in moisture, crude protein and crude ash contents, while crude lipid content a little bit fell during the transpmtation. In ordinaiy muscle under the first dorsal-fin, no changes in moisture and crnde protein were obtained, but crude lipid and glycogen contents were significantly decreased or crude ash content reversely increased immediately after the transpmtation. There were no remarkable difference in whole body fatty acid profile between pre- and pro-transportation. These revealed that the ship-transportation of PBF fingerlings rapidly decreased body, mainly ordinaiy muscle, lipid and glycogen as energy source even shortly transport distance and time.

This two-factor experiment incorporating three photoperiods (12L:12D, 16L:8D and 24L:0D) and two feeding methods (manual and self-feeding) was carried out to determine their effect on the growth performance of striped knifejaw, Oplegnathus fasciatus. Thirty juveniles were stocked into each 300 L tanks in triplicate for each treatment and fed a commercial diet for 10 weeks. Two-way ANOVA revealed that both photoperiod and feeding method have significant effect on the final mean weight, weight gain (%) and feed efficiency (FE) (P < 0.05); however, their interaction did not produce any significant effect (P > 0.05). Although the growth parameters didn't have significant difference between manual and self-feeding in fish exposed to 12L: 12D photoperiod (P > 0.05), fish under other two photoperiods showed significant improvement under self-feeding system compared to manual feeding (P < 0.05). Final mean body weights in fish under 16L: 8D and 24L: 0D were 119.7 and 124.0 g at manual feeding; however, increased to 128.0 and 133.7 g, respectively at self-feeding system. While two daily peaks of feed intake were observed in 12L: 12D and 16L: 8D photoperiods when self-feeders used, 24L: 0D photoperiod showed only one morning peak. At the end, there was no significant difference in different stress indicators such as cortisol, glucose and total protein among the treatments (P > 0.05). Finally, the results suggested that the extended (16L: 8D) and continuous (24 L: 0D) photoperiods, and the provision of self-feeder could significantly improve the growth performance of striped knifejaw without changing the stress response. Statement of relevance: This is the first report on the combined application of photoperiod manipulation and self-feeder on striped knifejaw, which revealed that the combination would help to improve the growth performance significantly. The indoor aquaculture industry, at least, will be benefited from the important insights achieved from this study to stimulate the growth performance of this commercially important species, which has great consumer demand in Japanese market. (C) 2015 Elsevier B.V. All rights reserved.

Red sea bream Pagrus major (RSB) weighing 0.09g were fed on test diets, composed of 65% fish meal supplemented with 0.49% Crataegi fructus (Cf) and a mixture of Massa medicata, Cf, Artemisia capillaries and Cnidium officinale (HM) or a control diet without herbs, in trial 1. After air exposure and anaesthesia treatment, higher stress tolerances were obtained in herbal groups than control group. Moreover, after challenge test with Vibrio anguillarum, mortalities of the herbal groups were lower than the control group. There was no significant difference in growth performance among the treatments. Feed efficiency (FE) of the test groups was 124-141%. In trial 2, RSB weighing 0.11g were fed on diets composed of 35% fish meal and 30% enzyme treated fish meal (EFM) with the same herbal treatments as trial 1. The herbal groups revealed higher final body weight and specific growth rate (SGR) and lower daily feed intake than those of the control group. The FE of test groups was 172-203%. These results indicate that the dietary herbs supplementation acts not only as recovery enhancer for some rearing stresses but also as growth enhancer, which is accelerated with dietary EFM in the early juvenile stage of red sea bream.

Three test diets were formulated using non-enzyme treated fish meal (FM) and fish oil with protein and lipid levels (%) of 55 and 18 (D1), 51 and 22 (D2), and 47 and 26 (D3) to determine the suitable dietary level as well as the utility of non-enzyme treated FM at grow-out stage of Pacific bluefin tuna (PBT), Thunnus orientalis. Raw sand lance, Ammodytes personatus (D4) with 64% protein and 11% lipid was used as the control. Duplicate groups of 100 young PBT (mean weight 82.9 g) were stocked into 6×6×4.5 m³ net cages and reared for 35 days. Although there was no significant difference in mean body weight between D1 and D4, D4 showed significantly higher value than that of D2 and D3 (P<0.05). The survival was significantly higher in fish fed with D1 (59.0%) than that of D4 (47.5%) (P<0.05). Dietary protein/energy ratio and protein content showed strong positive linear correlation with final mean weight. Relative weights of viscera, pyloric caeca and intestine in fish fed with D1-D3 were significantly higher than those of D4 (P<0.05). The increasing level of dietary lipid in D1-D3 resulted in significantly lower retention efficiency than that of D4 (P<0.05). Results suggest that the non-enzyme treated FM can be utilized and dietary level of 55% protein and 18% lipid could improve the growth performance as well as the survival of juveniles PBT at grow-out stage.

The present study was conducted to investigate the growth performance and feed utilization of marble goby, Oxyeleotris marmorata, juveniles fed with different levels of dietary lipid. Juvenile fish (initial mean weight 2.76 g) were fed with is onitrogenous diets including 10, 14, 18 and 22% of dietary lipid in triplicate groups for 15 weeks. The results showed that the highest growth performance and feed utilization was observed in fish fed D10. The increase of dietary lipid from 10 to 22 % did not improve growth, feed conversion rates, protein efficiency ratio, nitrogen retention efficiency, and apparent digestibility coefficients of protein and lipid (P>0.05). The increase of dietary lipid had significantly increased the whole body and hepatic lipid, hepato-somatic index, visceral-somatic index and intraperitoneal fat levels (P<0.05). These results suggest that there is no protein sparing effect of high dietary lipid levels inO. Marmorata due to possibly a limited ability to utilize dietary lipid. Based on the second-order polynomial regression analysis on protein efficiency ratio, ca. 12.1% of dietary lipid appears to be optimumfor growth from 2.76g to 13.76g body weight of O. marmorata juveniles.

Type I collagen is widely distributed in most organs in teleosts. It plays a role not only in intercellular adhesion, but also in molecular signaling. In this study, Pacific bluefin tuna (PBT) procollagen alpha 1 (I) cDNA was cloned and characterized. The nine fragments of a procollagen alpha 1 (I) chain cDNA clone were prepared and spliced together to create the complete coding region. The resulting amino acid sequence was homologous with that of other teleosts. The mRNA expression profile of PBT procollagen alpha 1 (I) in various tissues and the phylogenetic analysis with other vertebrate procollagen alpha 1 (I) chains suggest that PBT procollagen alpha 1 (I) could be a precursor form of the PBT type I collagen alpha 1 chain. In addition, its level of expression in PBT larvae and early juveniles gradually increased with somatic growth. This increase was related to the standard length, wet body weight, and protein content of each individual fish. Therefore, the expression profile of procollagen alpha 1 (I) may be a useful indicator for somatic growth in fish larvae and juveniles.

To determine a suitable dietary protein/lipid (CP/CL) ratio in the early juvenile stages of hybrid porgy (F1), female red sea bream (RSB) × male black sea bream, five diets with various CP/CL ratios-60/7, 55/12, 51/17, 46/23, and 41/28-were prepared and provided to juveniles in triplicate. At the smaller juvenile stage, F1, weighing 0.32 g, a significantly higher specific growth rate (SGR) and feed efficiency (FE) were seen with 60/7 and 55/12 diets. However, in RSB weighing 0.26 g, SGR and FE were higher with the 60/7 diet than the other diets at 21°C. At the larger juvenile stage, F1, weighing 3.7 g, there was no significant difference in SGR or FE among the diets, but RSB weighing 4.0 g fed 60/7, 55/12, and 51/17 diets had higher SGR and FE than 46/23 and 41/28 diets at 24°C. Moreover, survival and apparent nutrient retention of F1 at both stages were significantly higher than those in RSB. These results indicate that both F1 and RSB weighing ca. 0.3 g require a higher dietary CP/CL than those weighing ca. 4 g. Additionally, F1 in both trials showed the suitability of a lower dietary CP/CL than RSB, indicating that mass production of F1 juveniles will be more economical than RSB. © 2014 The Korean Society of Fisheries and Aquatic Science.

A feeding experiment was conducted to evaluate the efficacy of, and determine the requirements for dietary AsA (l-ascorbic acid) using its popular derivative l-ascorbyl-2-monophosphate-Mg (APM) for juvenile Pacific bluefin tuna (PBT). The five test diets (with APM-0, -400, -800, -1200 and -1600) were prepared by adding 0, 400, 800, 1200 and 1600 mg of APM kg diet(-1), respectively. These diets, together with chopped sand lance (the control diet), were administered, in duplicate to 0.27 g PBT at 25 days after hatching (300 juveniles per 15 m(3) tank). The PBT were fed to apparent satiety 6 times a day for 2 weeks. While final body weight, feed conversion and survival showed no differences among diets APM 400-1600, PBT fed APM-0 indicated lower growth performance together with anorexia, dark pigmentation and ataxia from 5 days and reached 80 % mortality at 12 days after the start of the feeding trial. In addition, liver and brain ascorbic acid (AsA) concentrations increased with increasing dietary APM levels, the values were similar in PBT fed diets with APM-1200 and APM-1600, and liver and brain concentrations of AsA were significantly higher in these fish than in the PBT fed the other diets (P < 0.05). The PBT responded to increasing dietary APM, and the fish fed APM-1200 had the highest weight gain, protein and lipid content. The data indicate that PBT can utilize APM as an AsA source and suggest that dietary supplementation with APM-1200 (454 mg AsA kg(-1) diet) would result in satisfactory growth.

The effect of five different light regimes on growth, stress and hematological indices was studied in Persian sturgeon, Acipenser persicus. Fish with average weight of 645.3 +/- 11.2 g were subjected to different photoperiods (24 L, 12 L:12 D, 16 L:8 D, 8 L:16 D and 24 D) for 8 wk. Blood samples were collected at the end of the experiment for measuring cortisol, glucose and hematological features. The whole growth parameters showed no significant difference. Plasma cortisol concentration was significantly higher in 12 L:12 D, while the lowest level was observed in fish exposed to 24 D. No significant changes were observed among the treatments for glucose concentration. Lactate concentration varied significantly among the treatments. Some hematological indices including hematocrit and number of white blood cells were affected by different light regimes, but the others (hemoglobin and number of red blood cells) were not affected significantly. The results showed that photoperiod manipulation can alters some stress-related metabolites and may enhance growth rate in fish exposing to continuous darkness.

The effect of dietary medicinal herbs, the herb mixture (HM) of Massa medicata, Crataegi fructus (Cf), Artemisia capillaries and Cnidium officinale, and single Cf, on various challenge and physical stress tests were examined for early three stages of striped jack. The larvae at 3 days after hatching, juveniles at the transportation from a land tank to a net cage and fingerlings at the body size before a shipment were given rotifer Brachionus plicatilis sp. complex and test diets, with or without the extract and fine powder of medicinal herbs, respectively. Final body weight of juveniles fed diets with the extracts was heavier than those fed diet without the extract. However, larvae fed rotifer with herb extract induced higher survival than those fed control rotifer without herbs against the challenge test with Vibrio anguillarum. The herbal groups of larvae, juvenile and fingerling showed slightly higher and shorter tendency in the survival and recovery time after air exposure than the control group. The herbal groups of juvenile showed shorter recovery time after the anesthesia than control group. Furthermore, the herbal groups of fingerling appeared longer LD50 time than control group against the low specific gravity stress. These results indicate the possibility that Cf and HM in rotifer and diets are useful to improve various stress resistance, connecting to the mass fingerling production of striped jack.

Taurine supplementation, to compensate for the reduction of fish meal (FM) in fish diets, has been the subject of numerous investigations. However, the taurine contents of FM-based diets are still lower than in diets of raw fish, even in diets where FM is the only protein source. In this study, the effect of taurine supplementation to commercial feed (containing 57% FM) on skin thickness and scale detachability in red sea bream Pagrus major was investigated. Three different levels of taurine were used: 0% taurine (control), 1% taurine (Tau-1%), and 2% taurine (Tau-2%). Red sea bream (average body weight, 107 g) were fed these diets for 60 days. No effects of taurine supplementation on growth and feeding efficiency were observed. However, skin thicknesses of fish from the Tau-1% and Tau-2% groups were significantly higher than for the control group, and scale detachability of the control group was significantly higher than for the Tau-1% and Tau-2% groups. These results suggested that taurine supplementation of commercial feed contributes little to growth performance, but does improve skin condition, in red sea bream.

Taurine supplementation, to compensate for the reduction of fish meal (FM) in fish diets, has been the subject of numerous investigations. However, the taurine contents of FM-based diets are still lower than in diets of raw fish, even in diets where FM is the only protein source. In this study, the effect of taurine supplementation to commercial feed (containing 57% FM) on skin thickness and scale detachability in red sea bream Pagrus major was investigated. Three different levels of taurine were used: 0% taurine (control), 1% taurine (Tau-1%), and 2% taurine (Tau-2%). Red sea bream (average body weight, 107 g) were fed these diets for 60 days. No effects of taurine supplementation on growth and feeding efficiency were observed. However, skin thicknesses of fish from the Tau-1% and Tau-2% groups were significantly higher than for the control group, and scale detachability of the control group was significantly higher than for the Tau-1% and Tau-2% groups. These results suggested that taurine supplementation of commercial feed contributes little to growth performance, but does improve skin condition, in red sea bream.

The effects of the dietary medicinal herbs Massa medicata, Crataegi fructus (Cf), Artemisia capillaries, Cnidium officinale and their mixture (HM), on growth and resistance against Vibrio anguillarum were examined using larval red sea bream, Pagrus major. The methanol extracts of Cf and HM inhibited the proliferation of seven infectious bacterial strains including the genera Aeromonas, Edwasiella, Photobavterium, Pseudomonas and Vibrio. Rotifers enriched with emulsified bonito oil containing extracts of Cf and HM lowered the bacterial counts in their body on TCBS medium for the genus Vibrio in comparison with rotifers enriched by emulsified bonito oil alone. Although statistically not significant, larvae fed rotifer fortified with Cf from 3 to 20 days after hatching showed the best growth and final body weight followed by those given rotifer with HM and control enrichment. However, final body length of larvae fed rotifer with Cf was significantly larger than larvae fed on rotifers enriched with other herb extracts. After a challenge test with V. anguillarum, survival of larvae fed rotifer with Cf and HM was significantly higher than for the control treatment. These results revealed that Cf and HM in rotifer is useful to promote growth and resistance against V. anguillarum in red sea bream larvae, providing a new technology for mass production of disease-resistant fry and fingerlings.

This study was carried out to investigate whether expensive enzyme-treated fish meal (EFM) can be partially replaced by soybean meal (SM) or enzyme-treated SM (ESM) without compromising the growth of captive-raised Pacific bluefin tuna (PBT) juveniles. Five fish diets were tested: EFM (control) and EFM in which 10 or 20% of the EFM was replaced with either ESM or SM (ESM(10), ESM(20), SM(10) and SM(20), respectively). The respective diets were provided to 28-day-old PBT juveniles (mean body weight approx. 0.38 g) stocked randomly in 15-m(3) tanks (276 juveniles per tank; two tanks per treatment) for 12 days. The final mean body weight of PBT juveniles on diets EFM, SM(10), and SM(20) was significantly higher than that of juveniles on diet ESM(20). Although daily feeding rate was significantly higher in the ESM and SM groups, feed efficiency (FE) was significantly higher in the EFM group; there was no significant difference between juveniles fed diets EFM and SM(10). Protein and phosphorus retention efficiency were significantly lower in the ESM(20), and ESM(20) and EFM groups, respectively. Phosphorus discharge was significantly lower in the SM groups. The results demonstrate that 10% SM (11% EFM replacement) can be included in EFM without compromising the growth performance of PBT juveniles.

Fish farming of sparids has started with the success in artificially hatched red sea bream (Pagrus major) larvae in Japan and domestication of sea bream (Sparus aurat) in the Mediterranean. Over the years the culture of these two species has developed into large-scale industries. This chapter focuses on production systems, covering with the hatchery stage, describing different rearing techniques and technologies, and finalizing with growout metabolic aspects and related environmental issues. Hatcheries of sparids include larval rearing, planktonic food chain production (both phytoplankton and zooplankton), and nursery sections. The process of larval rearing represents probably the major bottleneck of the rearing, as in all aquaculture activities. Hatcheries applying intensive or semi-intensive techniques are producing juveniles at size of 2-5 g that are transferred to an ongrowing cage or land-based systems, or may include a preongrowing period (up to a size of 10-30 g) in case of open sea cages. Floating cages in protected or semiprotected sites are the dominant technology used for the production of sea bream in the Mediterranean and are widely used for red sea bream in Japan aswell. Limited locations and increasing competition and conflicts with other users of coastal areas have promoted the development of offshore open sea cages. Land-based systems are used for sparids in Japan and in the Mediterranean for many years and developed from extensive to a modern and intensive production system, yet with limited use. The chapter also includes a quantitative description of four basic metabolic rates required for the design of a production system, using the sea bream as a model (growth feeding respiration of O2 and CO2 excretion of metabolites) and describes the required environment for culture in terms of water quality and photoperiod manipulations. At the last section, the impact of sparids production on environmental issues is discussed, including aspects of source impact, escapes, nutrient enrichment, and long-term sustainability issues. Finally, some future directions of research and development of sparids production systems is discussed, including further development of the mesocosm approach, advancing offshore technologies, and improving performances of land-based recirculating and integrated systems. © 2011 Blackwell Publishing Ltd.

A two-factor experiment incorporating two photoperiods (16 L:8 D and 24 L:0 D) and four feeding intervals (6, 9, 12 and 24 h) was carried out to determine the most efficient feeding interval and photoperiod for striped knifejaw, Oplegnathus fasciatus. Fish were fed a commercial diet to apparent satiation for 10 weeks. Blood was collected to measure the stress indicators. Both the photoperiod and the feeding intervals had a significant effect on the growth performance of striped knifejaw; however, their interaction did not produce any significant effect. The final body weight, weight gain (%) and feed intake at 6-, 9- and 12-h feeding intervals under 16 L:8 D were significantly higher than those at the 24-h interval irrespective of the photoperiod (P < 0.05). The specific growth rate at 6, 9 and 12 h intervals of the 16 L:8 D photoperiod was significantly higher than that of the other feeding intervals, except at 12 h of the 24 L:0 D photoperiod (P < 0.05). At the end of the experiment, there were no significant differences in the plasma levels of cortisol, glucose and total protein observed in fish exposed to different photoperiods compared with the initial levels. The results suggested that a combination of a 16 L:8 D photoperiod and either of 6-, 9- or 12-h intervals can be used to stimulate the growth performance in striped knifejaw.

Adult red sea bream, Pagrus major (body weight, 1.0-2.0 kg) was exposed to three photoperiods [12 h light:12 h dark (12L:12D), 16 h light:8 h dark (16L:8D) and 24 h light:0 h dark (24L:0D)] from 2 months before spawning till the end of the spawning season to investigate growth, spawning and stress response. During the spawning season, tanks were checked every morning for spawned eggs. The growth performance in fish under 24L:0D was stimulated with significantly higher feed intake than those under other photoperiods (P < 0.05). The number of eggs and gonadal histology confirmed that three and five females out of six in each of duplicate tanks of the 16L:8D treatment spawned. In contrast, only two out of six females in one tank of the 24L:0D treatment spawned, and no spawns were observed in the 12L:12D treatment. At the end of the spawning period, both 17 beta-estradiol and testosterone levels were significantly higher in fish exposed to 16L:8D followed by 12L:12D and 24L:0D photoperiods (P < 0.05). Photoperiod manipulation did not cause significant stress response in fish (P > 0.05). The results suggest that stimulating the growth performance of red sea bream at reproductive stage with a 24L:0D photoperiod is possible if the fish are subjected to this photoperiod long before the onset of the spawning season.

交雑魚F1（平均体重49g）における飼料魚粉（FM）に対する大豆粕（SBM）代替許容量とフィターゼ添加効果を、FM46％、FM30％＋SBM20％およびFM15％＋SBM40％から成る飼料F、S20およびS40と、S40＋フィターゼ2,500 units／kg飼料（S40P）を12週間給与して調べた。飼育試験は3反復区で実施した。いずれの区でも斃死は認められなかったが、飼料F区の飼育成績や栄養素蓄積率および消化率に比べて、S40区では有意に低下し、S40P区では類似するレベルにまで回復したが、S40区とS40P区の間には有意差はなかった。全魚体や肝臓の一般成分、血液性状および消化器官重量に、飼料助成の違いに基づくと考えられる区間差はなく、飼料S40P区では見かけのリン消化率と蓄積率は最も高く、環境水へのリン負荷率は最も低かった。以上の結果から、F1飼料でのSBM代替許容量は40％以下であったが、フィターゼ添加によりSBM40％飼料の利用性が大きく改善されることが分かった。

The present trial was conducted to determine the optimum proportion of dietary protein and lipid for juvenile Pacific bluefin tuna (PBT), a carnivorous fish possessing very high culture potentials in the Pacific region. Five test diets, D1-D5, were prepared with varying proportion of protein/lipid 72.8/9.2, 66.8/14.8, 61.9/17.9, 57.2/21.9, 53.3/27.0, respectively, using defatted enzyme treated fish meal and salmon egg oil. Raw sand lance (SL) was used as the control. The feeding trial started with each 200 juveniles of 25 days after hatch per 15 m(3) tank. having a mean body weight of 0.26 g. The diets were fed to duplicate groups, 6 times daily upto apparent satiation and reared for 10 days. At the end, growth performance was compared among the treatments. The D3 group showed the highest growth performance in terms of final body weight, specific growth rate and feed efficiency but with similar survival rate to the other groups. Carcass lipid content, and viscera and intestine somatic indices rose with increasing in dietary lipid content D3 fed fish had increased higher carcass 22:6n-3 and 22:6n-3/20:5n-3 ratio but lowered 14:0, 18:1n-9, 20:5n-3 and Sigma n-6 fatty acids as compared with those fed the other diets. These results demonstrated that the artificial formulated diet with 61.9% crude protein and 17.9% lipid could be used in juvenile tuna culture successfully. (C) 2008 Elsevier B.V. All rights reserved.

The growth performance and stress response in striped knifejaw, Oplegnathus fasciatus (body weight 100300 g) reared under four photoperiods (6L:6D,12L:12D,16L:8D and 24L:OD) were investigated. Fish were fed a commercial diet to apparent satiation, two times a day for 8 weeks. A trial of acute handling and confinement stress was also carried out to investigate the stress-induced levels of different stress indicators in O. fasciatus. Blood was also collected from undisturbed fish which was considered as control. Although there were no significant differences in weight gain, specific growth rate (SGR) and feed conversion efficiency (FCE) in fish exposed to 6L:6D, 16L:8D and 24L:OD photoperiods, all parameters in these photoperiods were significantly higher than those of 12L:12D photoperiod (P<0.05). There was no significant difference in protein retention efficiency (PRE) between fish exposed to 16L:8D and 24L:OD photoperiods, but PRE in both photoperiods was significantly higher than that of 12L:12D photoperiod. Acute stress significantly increased the plasma levels of cortisol (110.3 ng ml(-1)) and glucose (195.4 mg dl(-1)), and decreased plasma levels of total protein (0.8 g dl(-1)); however, all parameters were returned back to the levels indistinguishable from those of control, undisturbed fish within 24 h. The levels of cortisol, glucose and total protein in fish exposed to different photoperiods during the study were far from the stress-induced levels (P<0.05). The results demonstrated that the growth performance of O. fasciatus reared from 100 to 300 g can be stimulated significantly by using the manipulated photoperiods where feeding time may be playing an important role to increase food intake and feed conversion efficiency. It also revealed that the artificial photoperiods did not cause significant stress response in fish. (C) 2008 Elsevier B.V. All rights reserved.

[Abstract] This study was aimed to investigate whether photoperiod manipulation can be used to stimulate the growth performance without stress response in striped knifejaw Oplegnathus fasciatus with 280-350g body weight. Fish were fed a commercial diet to apparent satiation, two times a day for 9 weeks. Blood was also collected from the initial fish. Although there was no major variation in weight gain, specific growth rate, feed intake and feed conversion efficiency between 16L:8D and 24L:OD photoperiods, all parameters in these photoperiods were remarkable higher than those of 12L:12D photoperiod. There was no major difference in final whole body proximate composition among the treatments; however, retentions efficiencies of protein and energy, HSI and VSI in fish under 16L:8D photoperiod were remarkable higher than those of 12L:12D photoperiod. At the end, the plasma levels of cortisol, glucose and total protein in fish under the artificial photoperiods were similar to those of initial levels. The results demonstrated that the artificial photoperiod 16L:8D can be used to enhance the growth performance of 0. fasciatus without causing significant stress response.

Previous studies have shown that feeding enriched Artemia induces growth failure in Pacific bluefin tuna (PBT) Thunnus orientalis larvae. This growth failure cannot be improved even if the docosahexaenoic acid (DHA) content in enriched Artemia is elevated to the same level as that in yolk-sac larvae, an ideal live feed for PBT larviculture. This might be caused by the differences in the DHA in the live feeds; i.e., yolk-sac larvae of marine fish have a high level of DHA in the larval phospholipids (PLs) but enriched Artemia store DHA in their neutral lipids (NLs). To test this hypothesis two experiments were conducted to evaluate the effect of dietary PL rich in DHA on growth and survival of PBT larvae (Experiment 1) and juveniles (Experiment 2). Three isoproteic and isolipidic artificial test diets (Diets 1, 2 and 3) and two reference live feeds (Diets 4 and 5) were prepared. Diets 1 and 3 were supplemented with NL and PL fractions of commercial salmon Oncorhynchus gorbuscha roe lipid (SRL) as the lipid source, respectively, whereas Diet 2 was supplemented with a mixture of both lipid fractions. Diets 4 and 5 were enriched Artemia and yolk-sac larvae of Japanese parrot fish Oplegnathus fasciatus, respectively. Diets 1, 3, 4 and 5 were given to PBT larvae for 10 days, whereas Diets 1, 2 and 3 were fed to PBT juveniles for 10 days. In Experiment 1, the growth and survival of PBT larvae fed Diet 3 (high PL, fraction) were significantly improved when compared with larvae fed Diets 1 and 4, although the best growth and survival were obtained in larvae fed Diet 5. Similar results were obtained in Experiment 2; i.e., growth and survival were significantly improved in PBT juveniles fed Diets 2 and 3. In both experiments, fish fed Diets 2, 3 and/or 5 had higher total lipid contents, TAG levels, n-3 HUFA and/or DHA levels in NL fraction of the body when compared with fish fed Diets I or 4, while such a difference was not observed in the PL fraction. In juveniles over 90% of deaths were caused by collisions with the tank walls and the significant difference in mortality between treatments implies diet also affects behavior. SRL PL is concluded to enhance the growth and survival of PBT larvae and juveniles along with the accumulation of storage lipid and DHA in the body. (c) 2008 Elsevier B.V. All rights reserved.

Three photoperiods (12L:12D, 16L:8D and 24L:0D) were used to investigate the growth performance and stress response in red sea bream, Pagrus major (body weight 200-400 g). Fish were fed a commercial diet to apparent satiation, two times a day for 8 weeks. Fish exposed to a 24L:0D photoperiod showed a significantly higher weight gain (%) than those exposed to other photoperiods (P < 0.05). The best specific growth rate and feed conversion efficiency were achieved at 24L:0D and 16L:8D, without significant differences among them. Although fish exposed to 16L:8D showed a significantly higher plasma level of cortisol than those exposed to other photoperiods in the third week, there was no major variation in the cortisol level among the treatments either at the sixth week or at the end of this study. There were no significant differences either in the haematocrit level or the plasma levels of glucose, total cholesterol and total protein among the treatments during this study. The results revealed that the growth performance of red sea bream reared from 200 to 400 g can be stimulated significantly using a continuous (24L:0D) photoperiod without any measurable significant stress response in fish.

In order to develop an artificial diet, the dietary utility of enzyme-treated fish meal was investigated for juvenile Pacific bluefin tuna Thunnus orientalis (PBT). Diets containing each 63% of Chilean fish meal (FM), enzyme-treated Chilean fish meal (EC) and enzyme-treated Peruvian fish meal (EP), with 10% bonito oil and raw sand lance Ammodytes personatus (SL) were fed to juvenile tuna six times per day for one week. In a different trial, diets EC and SL were fed to tuna six times per day for 2 weeks. Only diet EC sustained similar growth or caused lower survival and higher feed efficiency, hepato- and enterosomatic indices and final carcass lipid content as compared to those of SL. Diets FM and EP led to lower specific growth rate (SGR) but similar feed efficiency, survival and hepatosomatic index, yet higher enterosomatic index. Moreover, PBT fed diet EC for 2 weeks led to similar growth performance but higher final carcass and hepatic lipid contents, and plasma cholesterol and phospholipid levels than those fed SL. Carcass fatty acid composition of diet EC group had lower 20:5 n-3 and 22:6 n-3 levels than the SL group. These results revealed that EC, as a suitable dietary protein source, could sustain growth of PBT, while dietary bonito oil led to higher carcass lipid but lower accumulation of n-3 highly unsaturated fatty acids.

This study was designed to determine the optimum dosage of phytase in soybean meal diets for red sea bream to produce good growth performance, digestibility and retention efficiencies of nutrients and energy, and to reduce phosphorus discharge of effluent rearing waters. Six isoenergetic diets were formulated: fish meal 65% (F), fish meal 40%+soybean meal 30% (S), and S supplemented with phytase at 1000, 2000, 3000 and 4000 phytase activity units (FTU) kg(-1) (SP1000, SP2000, SP3000 and SP4000, respectively). Twenty fish (initial mean weight ca. 24 g) were stocked into each of twelve 300-1 tanks and two tanks were assigned randomly to each diet. Fish were fed their respective diets for 6 weeks, twice daily until satiation to investigate the growth performance. Fish were then transferred into separate fecal collection columns to investigate digestibility. This experiment was run for another 4 weeks with a similar feeding protocol and 0.5% chromic oxide (Cr2O3) was included as an inert marker. The partial replacement of fish meal by soybean meal in diet S resulted in reduced weight gain, specific growth rate (SGR), digestibility and retention efficiencies of nutrients and energy; however, all parameters were increased significantly in fish fed diet SP2000 (P<0.05). Phosphorus discharge was also significantly reduced in fish fed diet SP2000 compared to the fish fed diets F and I S. The growth performance in fish fed diet SP2000 was as good as those fed diet F. Phytase dosage higher than 2000 FTU kg(-1) however, did not further improve growth performance. This suggests that the optimum dosage of phytase in the diet including 40% fish meal and 30% soybean meal was approximately 2000 FTU kg(-1) for red sea bream. (C) 2007 Elsevier B.V. All rights reserved.

Two consecutive feeding trials were conducted to know: (i) how the apparent digestibility coefficient (ADC) varies among replicates on different days and during the course of the experiment (Trial 1); and (ii) the effect of stocking density (e.g. 7.17, 5.56, and 3.92 kg fish/t water) on the ADC of nutrients and energy in red sea bream (Trial 2). In both trials, 0.5% Cr2O3 was used as an inert marker. In Trial 1, there were no significant differences in ADC within the replicates although the values on different days varied significantly during the second week. The ADC of all parameters in the third and fourth weeks was significantly higher than in the second week (P < 0.05). Although statistically insignificant, the lower stocking densities (3.92 and 5.56 kg fish/t water) showed better growth performance and superior ADC of protein, lipid, and energy than the higher stocking density in Trial 2. The results indicated that it may be better to acclimate fish to the diet for at least three weeks to obtain more reliable data by using a single tank for each treatment for digestibility experiments. Results also indicated that growth and digestibility performance can be stimulated by controlling stocking density.

This preliminary study was designed to investigate the influence of partial replacement of fish meal with soybean meal on digestive function of red sea bream, Pagrus major with or without phytase supplementation. Five isocaloric diets were formulated: F (70% fish meal), S₁₅ (55% fish meal + 15% soybean meal), S₂₅ (45% fish meal + 25% soybean meal), S₄₅ (25% fish meal + 45% soybean meal) and S₂₅ + P (S₂₅ + 3, 000 FTU phytase/kg diet) . Fish weighing about 78 g were fed these diets for 6 weeks at 21 ± 1°C . The partial replacement of fish meal with soybean meal resulted in a lower apparent digestibility coefficient (ADC) of nutrients and energy which resulted in lower food consumption and final body weight in red sea bream. However, the ADC of protein and energy, feed consumption, and final body weight in S₂₅ + P were higher than those of fish fed with S₂₅. Fish fed with S₂₅ + P showed remarkably lower phosphorus discharge than those fed with other diets (P <0.05) . The results demonstrated that fish meal replacement by soybean meal reduced the ADC of nutrients and energy; however, phytase supplementation in soybean meal diet increased the ADC of those parameters in red sea bream. In addition, phytase supplementation could help to reduce phosphorus discharge in the environment.

This study aimed to improve egg quality and seedling production through dietary docosahexaenoic acid (DHA) and soybean lecithin (SL) supplementation for striped knifejaw broodfish. Experimental white fish meal diet D1, D2 and D3 were added with both DHA (2%) and SL (3%), SL, and DHA, respectively. Three groups of broodfish, having mean body weight of 867 g in female and 1269 g in male, were fed with one of the diets, once a day, for 12 weeks. The D1 and D3 induced superior spawning performance tendency to D2. Highest buoyancy rate, hatching rate and SAT were found in D1 group and highest fecundity was observed in D3 group. The D2 group produced significantly lower egg weight and SAT (P<0.05) . The D1 and D3 group significantly increased egg, ovary and muscle DHA levels as compared with D2. However, dietary SL in D1 and D2 did not promote any noticeable change in egg, ovary, liver and muscle phospholipids contents. These results reveal that dietary DHA supplementation improves egg quality and early development in larvae.

Feeding ofArtemiaenriched with commercial enrichers (enrichedArtemia) induces the growth failure of the Pacific bluefin tuna (PBT) Thunnus orientalislarvae but feeding of yolk-sac larvae of marine fish promotes larval growth. However, the underlying causes of this phenomenon have never been explained. Therefore, in this study, two consecutive experiments, 1) a nutritional comparison among enriched rotifers, enrichedArtemia, and yolk-sac larvae of Japanese knifejawOplegnathus fasciatusand 2) a preliminary rearing trial of bluefin tuna larvae by feeding either enrichedArtemiaor yolk-sac larvae, were conducted to predict the possible nutritional cause (s) . No remarkable differences were found in proximate and amino acid compositions among the live feed, while phosphatidylchorine, sterol ester, and docosahexaenoic acid (DHA) levels were comparatively low in enrichedArtemia. The carbohydrate content in enrichedArtemiawas similar to that in enriched rotifers but higher than that in yolk-sac larvae. In the rearing trial for 6 days, the growth and survival of PBT larvae fed yolk-sac larvae were superior to those fed enrichedArtemia. The PBT larvae fed yolk-sac larvae had significantly higher levels of triacylglycerol and DHA. The results suggest that the nutritional inferiority of enrichedArtemiato yolk-sac larvae is partly responsible for the growth failure of PBT larvae fed enrichedArtemia.

This study was carried out to investigate the suitability of Artemia enriched with docosahexaenoic acid (DHA) and choline as live food on the growth and survival rate of the Pacific bluefin tuna (PBT; Thunnus orientalis) larvae. The PBT larvae were fed either Artemia enriched with oleic acid (Diet 1), DHA (Diet 2), DHA+choline 1.0 mg L-1 (Diet 3) and DHA+choline 2.0 mg L-1 (Diet 4) or striped knifejaw larvae (Diet 5, reference diet), in duplicate for 12 days. Enrichment of Artemia with DHA significantly increased the DHA levels to 13.9, 13.8 and 12.5 mg g(-1) on a dry matter basis in Diets 2, 3 and 4 respectively; however, the levels were significantly lower than the reference diet (26.9 mg g(-1) dry matter basis; Diet 5). Although growth and survival rate were significantly improved by the enrichment of Artemia with DHA and choline, the improvement was negligible compared with the enhanced growth and survival rate of the fish larvae-fed group (P < 0.05). The results demonstrated that enriched Artemia does not seem to be the right choice to feed the PBT larvae perhaps because of the difficulties in achieving the correct balance of fatty acid with higher DHA/EPA from Artemia nauplii.

Juvenile of red sea bream (Pagrus major, body weight 1 similar to 30 g) were reared under four photoperiods (6L:6D, 12L 12D, 16L:8D and 24L:0D) with constant light intensity 1500 1x on the water surface to investigate their growth performance and stress response. Fish were fed a commercial diet to apparent satiation for 8 weeks of the experiment. Significantly higher weight gain and specific growth rates (SGR) were observed in fish exposed to a 24L:0D photoperiod followed by 16L:8D, 6L:6D and 12L:12D photoperiods (P < 0.05). Food intake was significantly higher in fish exposed to 24L:0D followed by 6L:6D, 16L:8D and 12L:12D photoperiods (P < 0.05). There was no significant difference in the feed conversion efficiency (FCE) between fish exposed to 24L:0D and 16L:8D photoperiods, but the FCE in both photoperiods was significantly higher than that of 6L:6D and 12L: 12D photoperiods. There were no significant differences in hematocrit levels and plasma levels of cortisol and glucose among the treatments at the end of experiment. The results demonstrated that the growth performance of juvenile red sea bream reared from 1 to 30 g can be stimulated significantly by using a continuous (24L:0D) photoperiod without any measurable significant stress response in fish. (c) 2006 Elsevier B.V. All rights reserved.

A number of primary and secondary features used as stress indicators in fish were investigated in red sea bream, Pagrus major exposed to different photoperiod regimes. In Experiment 1, fish weighing from 17 to 25 g were subjected to acute stress consisted of netting the fish from the rearing tanks and confinement in a small tank (30 Q half-full of water. The fish were then sampled at 0.5, 1, 4, 24, 48, and 72 h post-stress to investigate the stress-induced levels of different parameters. In Experiment 2, fish were exposed to different photoperiods (6L: 6D, 12L: 12D, 16L: 8D and 24L: 0D) for eight weeks. Blood samples were collected from the fish at the 1st, 4th and 8th week after exposure to the photoperiods. Acute stress significantly increased the plasma levels of cortisol (190.1 ng ml(-1)) and glucose (109.5 mg dl(-1)) and returned back to the basal levels within 24 h. In contrast, plasma levels of cholesterol (180.5 mg dl(-1)), total protein (3.0 g dl(-1)), potassium (4.1 mmol l(-1)) and Ca++ (11.3 mg dl(-1)) were decreased significantly and returned to levels indistinguishable from those of control within 72 h except cholesterol, which did not recover within 72 h. In Experiment 2, fish exposed to 6L: 61), 16L: 8D and 24L: OD photoperiods had significantly higher cortisol levels than those exposed to the 12L: 12D photoperiod during the first week (P < 0.05); however, there was no major difference in cortisol levels among the treatments during other sampling times. There were no significant differences in other parameters among the treatments during the course of the study (P > 0.05). Fish exposed to the 24L: OD photoperiod showed significantly higher weight gain and SGR followed by 16L: 8D, 6L: 6D and 12L: 12D photoperiods. The plasma levels of different stress indicators in different photoperiods in Experiment 2 were far lower than those of acute stress-induced levels observed in Experiment 1. On the other hand, no apparent signs of chronic stress were observed in fish exposed to different photoperiods. The results demonstrated that photoperiod manipulation caused no significant acute or chronic stress response in red sea bream. (c) 2005 Elsevier B.V. All rights reserved.

Two consecutive trials were conducted to investigate the effects of photoperiod manipulation on growth rate, food intake and feed conversion efficiency (Trial 1), and the digestibility of nutrients and energy (Trial 2) in red sea bream, Pagrus major (body weight 19-120 g). Fish were exposed to four photoperiods (6L:6D, 12L:12D, 16L:8D and 24L:0D) with light intensity 1500 Ix on the water surface. The fish were fed with a commercial diet to apparent satiation. In Trial 2, 0.5% chromic oxide (Cr2O3) was used as an inert marker. Significantly higher weight gain and specific growth rates were observed in fish exposed to a 24L:OD photoperiod followed by 16L:8D, 6L:6D and 12L:12D photoperiods (P<0.05). Food intake and feed conversion efficiency (FCE) were also significantly higher in fish exposed to 24L:0D followed by 16L:8D, 6L:6D and 12L:12D) photoperiods (P<0.05). Fish exposed to 24L:OD and 16L:8D photoperiods showed significantly higher lipid and energy digestibility than those exposed to a 12L:12D photoperiod (P<0.05). The results demonstrated that the enhancement of growth performances under 16L:8D and 24L:0D photoperiods were attributed to improved appetite, greater food intake and higher feed conversion efficiency as well as higher digestibility. (c) 2005 Elsevier B.V. All rights reserved.

A major problem in tilapia aquaculture is the frequent reproduction of female fish, leading to increased competition for supplemented food and stunted somatic growth. The feasibility of using photoperiod manipulation to arrest the reproductive performance of tilapia Oreochromis niloticus was therefore examined. Newly hatched O. niloticus were reared in the laboratory under 12L:12D photoperiod at 28 degreesC. Fish (230-340 g) were maintained under 6L:6D, 12L:12D and 14L:10D photoperiod at 28 degreesC during the course of this study. Effect of photoperiod manipulation on reproductive parameters of fecundity, gamete quality, offspring viability and overall reproductive success were evaluated. Steroid levels (estradiol-17ss, E-2; testosterone, T) during the spawning cycles of fish were analyzed on days 1 and 3 postspawning and at 3-day intervals thereafter. A total of 72 female fish from each photoperiod treatment were investigated the changing pattern of E-2, T and GSI with fish that have spawned once, twice and three times. Fish exposed to 12L: 12D and 14L: 10D photoperiod spawned successfully throughout the to 6L:6D photoperiod was arrested after three to four spawning cycles. The arrestment of spawning in fish exposed to 6L:6D photoperiod was paralleled by a significant decrease in plasma levels of E2 (P<0.05). By contrast, there was no major difference in T levels among the treatments. These findings suggest that photoperiod manipulation can be used to arrest the spawning in tilapia O. niloticus. The utility of this in controlling the problem of overcrowding due to excess offspring in tilapia aquaculture is applicable. (C) 2004 Elsevier B.V. All rights reserved.

After conditioning Nile tilapia Oreochromis niloticus for 2 weeks, the photoperiod regime of 12 tanks of fish was changed to a 6L:6D photoperiod while 12 further tanks were retained on the conditioning photoperiod regime (12L:12D). Blood samples were collected 3 days (first sampling) and 3 months (second sampling) after changing the photoperiod regime. Blood was collected at 6 h intervals from both photoperiod regimes (1000, 1600, 2200 and 0400 hours). At the first sampling time, fish in the 6L: 6D had significantly higher cortisol both in the light and dark phases than levels in fish in the 12L:12D photoperiod. At the second sampling time, the levels were significantly higher only in the light phase. The levels of cortisol, glucose and Cl- in fish exposed to the 6L:6D photoperiod, however, were far lower than those of acute stress-induced levels observed in fish exposed to a stress experiment. Furthermore, there were no significant differences in overall values of all the variables between the photoperiod regimes at the second sampling time. This indicated that the fish exposed to the 6L:6D photoperiod were not chronically stressed. Significantly higher blood lymphocyte counts were observed in fish exposed to the 6L:6D compared to those of the 12L:12D photoperiod during the light phase at the second sampling time. Other variables (glucose, Cl-, haematocrit and neutrophil) did not show a significant difference between the treatments at either sampling time. These results demonstrated that the artificial photoperiod regime did not cause a significant acute or chronic stress response in Nile tilapia. (C) 2004 The Fisheries Society of the British Isles.

The effects of photoperiod (PPD) and feeding interval on food intake and growth of Nile tilapia Oreochromis niloticus were investigated. In the first two trials, fish were subjected to PPD of 3L: 3D (3LD), 6L : 6D (6LD), 12L: 12D (12LD) and 24L: 24D (24LD) for 6 weeks at 28degreesC. In Trial 1, the fish (mean weight 3.45 g) were fed 5% of body weight per day and in Trial 2 fish (mean weight 3.60 g) were fed to visual satiation (four meals per day) according to the feeding interval specified for different treatments. In a third trial, fish subjected to 12LD were fed 6% of body weight per day and fish were given 12% every other day under 24LD. Fish exposed to a 6LD PPD had a significantly higher growth rate than those exposed to other PPD in Trials 1 and 2 (P < 0.05). When the fish were fed to satiation, significantly higher food consumption and feed efficiency (P < 0.05), and lower adiposity (P < 0.05) were observed in fish exposed to 6LD PPD than those exposed to 12LD PPD. These results indicated that a 6LD PPD regimen resulted in an improvement of fish growth through stimulated food intake. Thus, these experiments suggested that the growth of Nile tilapia could be controlled by the manipulation of PPD and feeding interval.

To study the influence of different photoperiod cycles on the metabolic rate and energy loss of fed and unfed adult tilapia Oreochromis niloticus (bodyweight 102-107 g) at 28degreesC, four photoperiod cycles (i.e. 3L: 3D, 6L: 6D, 12L: 12D, and 24L: 24D) were applied. A computer-operated respirometer with a closed tank was used so as to prevent water from condensing from the air or evaporating into the air. A photoperiod-mediated metabolic cycle was demonstrated during the routine state in which the metabolic rate was higher during the light phase compared with during the dark phase for all photoperiods. The combined effects of photoperiod and feeding episodes acted as a strong Zeitgeber (cue or synchronizer) for synchronizing the daily rhythm in fed fish. Fish exposed to short photoperiod cycles showed a higher metabolic rate and energy loss compared with those exposed to longer photoperiod cycles. Mean oxygen consumption in the fed and unfed fish were 295.7 mg/kg per h and 149.8 mg/kg per h, respectively, during the 3L: 3D period; 286.5 mg/kg per h and 143.3mg/kg per h during the 6L:6D period; 262.2 mg/kg per h and 130.3 mg/kg per h during the 12L: 12D period; and 238.3 mg/kg per h and 120.4 mg/kg per h during the 24L: 24D period. The highest post-prandial increase in energy loss was recorded during the 3L: 3D period (56.2 kJ/kg per day), followed by 55.1 kJ/kg per day during the 6L: 6D period, 50.7 kJ/kg per day during the 12L: 12D period, and 45.4 kJ/kg per day during the 24L: 24D period. The study's results demonstrated that the fish conserve energy when raised under longer photoperiod cycles.