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1.
An optimal flow domain in culture tanks is vital for fish growth and welfare. This paper presents empirical data on rotational velocity and water quality in circular and octagonal tanks at two large commercial smolt production sites, with an approximate production rate of 1000 and 1300 ton smolt/yr, respectively. When fish were present, fish density in the two circular tanks under study at Site 1 were 35 and 48 kg/m3, and that in four octagonal tanks at Site 2 were 54, 74, 58 and 64 kg/m3, respectively. The objective of the study was twofold. First, the effect of biomass on the velocity distribution was examined, which was accomplished by repeating the measurements in empty tanks under same flow conditions. Second, the effect of operating conditions on the water quality was studied by collecting and analysing the water samples at the tank’s inlet and outlet. All tanks exhibited a relatively uniform water velocity field in the vertical water column at each radial location sampled. When fish were present, maximum (40 cm/s) and minimum (25–26 cm/s) water rotational velocities were quite similar in all tanks sampled, and close to optimum swimming speeds, recommended for Atlantic salmon-smolt, i.e., 1–1.5 body lengths per second. The fish were found to decrease water velocity by 25% compared to the tank operated without fish. Flow pattern was largely affected by the presence of fish, compared to the empty tanks. Inference reveals that the fish swimming in the tanks is a major source of turbulence, and nonlinearity. Facility operators and culture tank designers were able to optimize flow inlet conditions to achieve appropriate tank rotational velocities despite a wide range of culture tank sizes, HRT’s, and outlet structure locations. In addition, the dissolved oxygen profile was also collected along the diametrical plane through the octagonal tank’s centre, which exhibits a close correlation between the velocity and oxygen measurements. All tanks were operated under rather intensive conditions with an oxygen demand across the tank (inlet minus outlet) of 7.4–10.4 mg/L. Estimates of the oxygen respiration rate in the tank appears to double as the TSS concentration measured in the tank increases from 3.0 mg/L (0.3 kg O2/kg feed) up to 10–12 mg/L (0.7 kg O2/kg feed). Improving suspended solids control in such systems may thus dramatically reduce the oxygen consumption and CO2 production.  相似文献   

2.
The addition of a yeast culture food supplement (DVAqua from Diamond V. Mills, Cedar Rapids, IA, USA) was evaluated during feeding of McConaughy strain rainbow trout Oncorhynchus mykiss. Two trials were run consecutively, starting with initial feeding, and were replicated over 2 years. The yeast culture was added to commercial trout starter at levels of 0.125 and 0.25 g kg?1. The number of rainbow trout that died during the first 4 weeks of rearing was significantly reduced in the tanks receiving either of the yeast culture‐supplemented diets compared with the tanks receiving a control starter diet. Ending tank weights and gain were significantly and consistently greater in the tanks fed the 0.25 g kg?1 yeast culture diet. Individual fish weights were also significantly heavier in the fish‐fed yeast culture containing diets in each year of the study at the end of 27 days. In the trials from 4 to 8 weeks postinitial feeding, mortality rates were significantly less only in the tanks receiving 0.25 g kg?1 yeast culture supplementation. Individual fish lengths and weights at the end of the second trial were significantly greater in the tanks receiving either level of yeast culture compared with the control diet only in 1 year. Total tank weights and feed conversion were not significantly different between any of the treatments. The inclusion of DVAqua yeast culture provided significant increases in trout survival and growth through the first 4 weeks of feeding, with continued benefits for the next 4 weeks.  相似文献   

3.
Oxygen consumption, carbon dioxide excretion and nitrogen excretion from 2 kg Atlantic salmon Salmo salar L. were studied at land-based outdoor tanks, throughout a 10 day period. Fish were fed six feed rations (0 [fasting fish], 0.15, 0.30, 0.45, 0.60 and 0.75% BW day-1) of commercially extruded dry feed at two provision regimes: between 07.00-09.00 h and 19.00–21.00 h (periodic feeding); and between 07.00-21.00 h (continuous feeding). Fish were acclimatized to the feeding regime for 5 days prior to the start of the experiment. From days 5 to 10 of the study, oxygen consumption was measured automatically every 15 min. During day 10, carbon dioxide excretion, ammonia and urea excretion were measured hourly throughout a 24 h period. During the experiment, the water temperature and salinity were 8.5C and 33.5 ppt, respectively. Significant linear relationships between feed ration and metabolic rates were evident. Increased feed ration influenced oxygen consumption, carbon dioxide excretion, ammonia and urea excretion, ammonia quotient and the respiration quotient, proportionally. The two feed provision regimes caused the establishment of different daily rhythms in metabolic excretion. Only small differences in total daily excretion were however recorded for each feed ration. Ammonia and respiratory quotient results clearly showed that fish became more dependent on fat oxidation as an energy source, when feed was restricted.  相似文献   

4.
Triplicate groups of gilthead sea bream, Sparus aurata (10.4 g), were distributed among 27 tanks (12 fish per tank) and reared in flow‐through seawater. A factorial experiment (3 × 3) was designed to include a continuously fed control group and two cycled starvation groups: 1 + 3 (starved 1 d, fed 3 d), 1 + 5 (starved 1 d, fed 5 d). Each of the feeding groups was subjected to one of three feeding frequencies (2, 4, and 6 times per day) over the 60‐d experiment duration. The average final weight of fish in 1 + 3 and 1 + 5 groups were significantly lower than that of the control group. Partial compensation was observed in the starved groups subjected to any of the three feeding frequencies. Regardless of the feeding frequency, control fish consumed less feed than the starved groups. The highest body protein content was found in the control group. The rate of oxygen consumption significantly increased 30 min after the feeding and the magnitude of the effect increased with the feeding frequency. These results suggest that the present cycling starvation schedules did not invoke a full compensation in gilthead sea bream.  相似文献   

5.
The effect of feeding frequency (one, three, and continuous feeding), feed ration (0.2, 0.5, 0.8% of total fish biomass), and feeding per se on the oxygen consumption (OC, mg O2 kg−1 h−1) and ammonia excretion (AE, mg TAN kg−1 h−1) of juvenile tench (body weight 15–19 g) and variations in these parameters in daily cycles were examined. Fish metabolism was studied in a recirculating system (rearing tanks of 0.2 m3, water temperature 23 °C). It was found that oxygen consumption and ammonia excretion depended significantly on feed ration. An increase of feed ration from 0.2 to 0.8% of fish biomass caused an increase of OC and AE from 126.80 mg O2 kg−1 h−1 and 1.95 mg TAN kg−1 h−1 to 187.35 mg O2 kg−1 h−1 and 8.80 mg TAN kg−1 h−1 (p<0.05). There was no dependence between feeding frequency and the mean rate of oxygen consumption. However, the relationship between feeding frequency and ammonia excretion by juvenile tench was statistically significant (p<0.05). Feeding frequency significantly affected daily fluctuations of AE and OC. It was found that diurnal variations in metabolic rates were strictly related to tench feeding, and the daily variations of AE were significantly higher than OC.  相似文献   

6.
This study aimed at comparing fatty acid contents of rotifers cultured with different methods after nutritional enrichment in order to evaluate the rotifer quality produced by these methods. Rotifers were cultured using either a batch or a continuous culture. From the batch culture, three experimental subpopulations were used, sampled from the culture at 1, 24, and 48 h after rotifer inoculation. The continuous culture was performed with two tanks; one was for cultivation with continuous feeding and water supply (cultivation tank), and another was for harvesting from the cultivation tank by overflow (harvest tank). From the continuous culture, two subpopulations were used: one from the cultivation and one from the harvest tank. Nutritional enrichment was performed after each culture. Each population was enriched with Nannochloropsis oculata or a commercial enrichment diet. When the enrichment was performed with N. oculata on populations at 24 h after inoculation originating from either of the two tanks of continuous culture or the batch culture tank, a higher quantity of arachidonic acid (ARA) and eicosapentaenoic acid (EPA) was obtained from the two tanks of continuous culture. The same results were obtained when enrichment diet was used, this time including docosahexaenoic acid (DHA).  相似文献   

7.
A 10‐wk feeding trial to determine the effect of daily feeding ratio on growth and body composition of subadult olive flounder fed the extruded pellet (EP) was performed during the summer season. Thirteen flounder (an initial body weight of 319 g) per tank were distributed into fifteen 500‐L flow‐through tanks. Five treatments of feeding ratio in 5% decrement were prepared in triplicate: 100 (satiation), 95, 90, 85, and 80% of satiation. Fish in the control group (100% of satiation) were hand‐fed to apparent satiation twice a day. Then, feed allowance in the rest of the four groups was determined based on average feed consumption of fish in the control group. Weight gain of fish fed to 100% of satiation was significantly (P < 0.05) higher than that of fish fed to 85 and 80% of satiation but not significantly (P > 0.05) different from that of fish fed to 95 and 90% of satiation. Serum total protein, glucose, and glutamic pyruvic transaminase were not significantly (P > 0.05) affected by feeding ratio but triglyceride and glutamic oxaloacetic transaminase were. In considering these results, it can be concluded that optimum daily feeding ratio for growth of subadult olive flounder seemed to be 90% of satiation when fish were fed the EP twice a day during the summer season.  相似文献   

8.
Two experiments were conducted to examine whether a mixture of bacteria composed of Bacillus licheniformis, Bacillus subtilis and Bacillus pumilus has a beneficial impact on survival, growth, lysozyme activity and total immunoglobulins (Ig) in perch larvae. In experiment 1, control fish were compared with fish receiving bacteria (4.93 × 107 CFU L−1 day−1) through tank water or both through tank water and Artemia metanauplii enriched with two bacteria doses (2 × 1010 or 4 × 1010 CFU L−1). Treatments were performed in 40 L triplicate tanks of 200 fish [initial body weight (IBW)=2.3 mg] each, placed in separated recirculating water systems. Experiment 2 evaluated the combining effects of bacteria feeding and densities (10 vs. 20 fish L−1, IBW=9.5 mg). In both experiments, the bacteria added to live food or both live food and water induced higher growth rate at the highest dietary dose and this was associated with higher Ig levels on days 14 and 28. In experiment 2, higher survival was associated to lower type‐2 cannibalism (ingestion of whole prey) at the two dietary bacteria doses, and such positive effect was observed for fish fed bacteria at high density. Bacteria administration through water had no effect on growth and survival. In conclusion, the results show that high dietary concentrations of the mixture of bacteria used have potential stimulating impact on growth, survival, lysozyme activity and total Ig. But, further investigations are needed to demonstrate the optimal doses for emphasizing immune defence status.  相似文献   

9.
An 8 weeks growth study was conducted to estimate the optimal feeding rate for juvenile grass carp (3.08±0.03 g, mean ± SD). Fish were fed with a casein purified diet (360 g protein, 56 g lipid and 3000 kcal total energy/kg dry diet) at six feeding rates: 1.0, 1.5, 2.0, 2.5, 3.0, 3.5% body weight per day (BW d−1). Each feeding rate was randomly assigned to three tanks of fish with 30 fish per tank (50W × 50H × 100L, cm). Fish were maintained in recirculating systems at a water temperature of 24.97±2.23 °C and were fed four times per day. After 2 weeks, fish fed on 3.5% BW d−1 could not finish the diet and this treatment was cut-off. Analysis of variance showed that growth performance was significantly (p<0.05) affected by different feeding rates. The nutrient compositions of whole body, muscle and liver were also significantly different among treatments. The body weight gain (WG), specific growth rate (SGR), feed efficiency (FE), protein efficiency ratio (PER), apparent digestibility coefficiency (ADC), retention of protein (PR), mesenteric fat index, body moisture and protein content were significantly (p<0.05) affected by feeding rate. The WG, SGR and digestion rate were highest at 2% BW d−1, although the FE and PER decreased with increasing feeding rate. Broken line analysis on specific growth rate indicated that the optimum feeding rate of juvenile grass carp is 1.97% body weight day−1.  相似文献   

10.
The aim of this project was to investigate if lumpfish can be fed using specially designed feed blocks instead of regular fish feed pellets. Two studies were performed. In Part I different designs of feed blocks were introduced and fish observed with underwater cameras to record feeding behaviour. Results indicate that lumpfish require feed blocks with grooves in order to graze from them and that the acclimation period is relatively short (2–4 hr) before the fish will use them as a feed source. In the second part of the project two duplicate groups of lumpfish with an initial mean (±SD) weight of 125.4 ± 45.7 g were individually weighed and randomly distributed into six 3.5 m3 circular flow‐through tanks with 45 fish in each tank. Fish in three tanks were fed using feed blocks with grooves and fish in three tanks were fed using a regular commercially available lumpfish extruded feed. Both groups received a daily feeding rate of 2% body/weight. From day 14 onwards, fish fed with marine pelleted feed had a significantly higher mean weight compared to fish fed with feed blocks. Although not significant, the condition factor was higher in the feed block group during the study period. Results from this study show that lumpfish will readily graze from feed blocks if they are presented in a way that allows them to do. In addition, the acclimation period required before the fish will utilize them appears to be short thus potentially allowing for their use in commercial salmon cages.  相似文献   

11.
Oxygen consumption and ammonia excretion of black carp (Mylopharyngdon piceus Richardson) (4.6 ± 0.3 g) and allogynogenetic crucian carp (Carassius auratus gibelio ♀ × Cyprinus carpio ♂) (5.7 ± 0.5 g) were examined when fish fed two types of carbohydrate (dextrin and glucose) at two levels (20 and 40%) each. The diets were isonitrogenous (40% dry matter) and isocaloric at 18.5 kJ g−1 (dry matter) by adjusting the oil content to 10.1 and 1.5%, respectively. In black carp, the interactions between the carbohydrate type and level were found in oxygen consumption at 3 and 6 h and in ammonia excretion at 6 h after feeding. At 20% carbohydrate, no significant difference was observed between dextrin and glucose in oxygen consumption. However, at 40% carbohydrate, oxygen consumption in fish fed glucose was significantly higher than that in fish fed dextrin at 3 and 6 h after feeding. Within the dextrin diets, no significant differences in both oxygen consumption and ammonia excretion were detected between the two carbohydrate levels. Within the glucose diets, however, fish fed 40% glucose showed significantly higher oxygen consumption than those fed 20% glucose at 3 and 6 h after feeding. Ammonia excretion in black carp fed 40% glucose was higher than that in black carp fed 40% dextrin at 6 h and also found higher than those in the other three treatments at 24 h after feeding. The postprandial oxygen consumption and the ammonia excretion in crucian carp fed 40% glucose were the highest, but no significant differences were observed. Our data indicate that the escalation of glucose to 40% in a fish diet results in high oxygen consumption and ammonia excretion in black carp, suggesting that the efficiency of glucose as an energy source for this fish is compromised by the high metabolic expenditure after feeding. Crucian carp, on the other hand, have a better ability to cope with dietary carbohydrates.  相似文献   

12.
Walleye (Sander vitreus) is an important game fish throughout much of North America. We evaluated the performance of the Wisconsin bioenergetics model for walleye in the laboratory. Walleyes were fed rainbow smelt (Osmerus mordax) in four laboratory tanks during a 126-day experiment. Based on a statistical comparison of bioenergetics model predictions of monthly consumption with the observed monthly consumption, we concluded that the bioenergetics model significantly underestimated food consumption by walleye in the laboratory. The degree of underestimation appeared to depend on the feeding rate. For the tank with the lowest feeding rate (1.4% of walleye body weight per day), the agreement between the bioenergetics model prediction of cumulative consumption over the entire 126-day experiment and the observed cumulative consumption was remarkably close, as the prediction was within 0.1% of the observed cumulative consumption. Feeding rates in the other three tanks ranged from 1.6% to 1.7% of walleye body weight per day, and bioenergetics model predictions of cumulative consumption over the 126-day experiment ranged between 11 and 15% less than the observed cumulative consumption.  相似文献   

13.
A feeding trial was conducted in a recycling water system during 10 weeks to determine the optimal protein to lipid ratio in Asian red‐tailed catfish (Hemibagrus wyckioides). Six diets of two protein levels (390 and 440 g kg?1) with three lipid levels (60, 90 and 120 g kg?1) were formulated. Fish (1.96 g) were fed six diets with four replicates to apparent satiation at a stocking density of 50 fish per tank (500 L). Faeces were collected in cultured tanks at the end of the feeding trial for digestibility measurement. Significantly, improved growth performances (P < 0.01) and higher feed utilization (P < 0.001) were observed in fish fed with higher lipid diets. However, higher protein diets did not significantly improve fish growth but they reduced FCR (P < 0.001) and protein efficiency ratio (P < 0.01). Higher lipid diets also resulted in significantly increased adipose‐somatic index, carcass fat and reduced moisture of the fish. The study revealed the protein sparing effect of dietary lipid in the catfish and highest growth performance was found by fish fed 390 g kg?1 protein and 120 g kg?1 lipid diet with P/E ratio of 20.48 mg protein kJ?1. DP/DE ratio for maximal growth rate in diets was 21.48 mg protein kJ?1.  相似文献   

14.
A feeding trial was conducted to evaluate the potential of replacing fish meal with co‐extruded wet tuna viscera and corn meal in diets for juvenile white shrimp Litopenaeus vannamei. Five practical diets were formulated to contain 30% crude protein and 16.6 kJ g?1. The feeding experiment was carried out in a recirculating seawater system with fifteen 25‐L tanks with 15 shrimp per tank. Each dietary treatment was fed in triplicate in a completely randomized design for 41 days. Percent weight gain (WG%), survival (S%) and feed conversion ratio (FCR) were calculated, comparisons of these parameters showed no statistical differences (P>0.05) among treatments. The shrimp almost tripled their weight during the feeding trial. Under the experimental conditions S%, WG% and FCR were either improved or were not significantly influenced by the replacement of fish meal with double co‐extruded viscera+corn, except for a slight increase in feed consumption without affecting FCR. Hence, this product can be included by up to 40% in practical shrimp diets without any detrimental effects.  相似文献   

15.
The influence of stocking density and feeding regime on the growth of red porgy was studied during winter and spring 1997. Fish were held in 500-L tanks at densities of either 50 or 100 fish per tank, and were fed by means of self-feeders under 6 h restricted (day or night) or free-access feeding regimes. Fish were tagged individually, and weight gain was recorded by individual weighing every second week over an 8-week period during each season. In winter, growth was influenced by feeding time. Fish tended to grow best when fed without restriction and worst when fed at night, although differences were not significant when tank means were compared. Stocking density was influential in the spring trial. Fish stocked at low density and feeding freely grew better than high-density fish that fed either freely or at night. The division of fish into three size classes revealed that, within each treatment, no differences occurred among classes, but growth of fish belonging to the same class was influenced by rearing conditions. No significant differences were found among feeding regimes in terms of the coefficients of weight variation ratio (CVf:CVi) and feed efficiency.  相似文献   

16.
A low‐head recirculating aquaculture system (RAS) for the production of Florida pompano, Trachinotus carolinus, from juvenile to market size was evaluated. The 32.4‐m3 RAS consisted of three dual‐drain, 3‐m diameter culture tanks of 7.8‐m3 volume each, two 0.71‐m3 moving bed bioreactors filled with media (67% fill with K1 Kaldness media) for biofiltration, two degassing towers for CO2 removal and aeration, a drum filter with a 40‐µm screen for solids removal, and a 1‐hp low‐head propeller pump for water circulation. Supplemental oxygenation was provided in each tank by ultrafine ceramic diffusers and system salinity was maintained at 7.0 g/L. Juvenile pompano (0.043 kg mean weight) were stocked into each of the three tanks at an initial density of 1.7 kg/m3 (300 fish/tank). After 306 d of culture, the mean weight of the fish harvested from each tank ranged from 0.589 to 0.655 kg with survival ranging from 57.7 to 81.7%. During the culture period, the average water use per kilogram of fish was 3.26 or 1.82 m3 per fish harvested. Energy consumption per kilogram of fish was 47.2 or 22.4 kwh per fish harvested. The mean volumetric total ammonia nitrogen (TAN) removal rate of the bioreactors was 127.6 ± 58.3 g TAN removed/m3 media‐d with an average of 33.0% removal per pass. Results of this evaluation suggest that system modifications are warranted to enhance production to commercial levels (>60 kg/m3).  相似文献   

17.
A 9‐week feeding experiment was conducted to determine the dietary biotin requirement of Japanese seabass, Lateolabrax japonicus C. Six isonitrogenous and isoenergetic purified diets (Diets 1–6) containing 0, 0.01, 0.049, 0.247, 1.238 and 6.222 mg biotin kg?1 diet were fed twice daily to triplicate groups (30 fish per group) of fish (initial average weight 2.26 ± 0.03 g) in 18 fibreglass tanks (300 L) filled with 250 L of water in a flow‐through system. Water flow rate through each tank was 2 L min?1. Water temperature ranged from 25.0 to 28.0 °C, salinity from 28.0 to 29.5 g L?1, pH from 8.0 to 8.1 and dissolved oxygen content was approximately 7 mg L?1 during the experiment. After the feeding experiment, fish fed Diet 1 developed severe biotin deficiency syndromes characterized by anorexia, poor growth, dark skin colour, atrophy and high mortality. Significant lower survival (73.3%) was observed in the treatment of deficient biotin. The final weight and weight gain of fish significantly increased with increasing dietary biotin up to 0.049 mg kg?1 diet (P < 0.05), and then slightly decreased. Both feed efficiency ratio and protein efficiency ratio showed a very similar change pattern to that of weight gain. Dietary treatments did not significantly affect carcass crude protein, crude lipid, moisture and ash content. However, liver biotin concentration (0–6.1 μg g?1) significantly increased with the supplementation of dietary biotin (P < 0.05), and no tissue saturation was found within the supplementation scope of biotin. Broken‐line regression analysis of weight gain showed that juvenile Japanese seabass require a minimum of 0.046 mg kg?1 biotin for maximal growth.  相似文献   

18.
ABSTRACT

A 24-week feeding trial was conducted in concrete tanks with Nile tilapia, Oreochromis niloticus (L.) with an average initial weight and length of 50.87 ± 6.03 g and 14.4 ± 0.45 cm, respectively, to examine the effect of two protein sources and two feeding frequencies on growth performance, production traits, and body composition. Twelve 4 m3 concrete tanks (2 × 2 × 1.25 m, long, width, and height) were each stocked with 100 fish and fed diets containing either fish meal protein or soybean meal protein at two feeding frequency of two times daily or four times daily (2 × 2 × 3 factorial experiment). The results revealed that there was no significant effect of dietary protein sources on growth rate, whereas there was a significant increase in growth rate with increasing feeding frequency (P < 0.05). The same trend was also observed for mean body weight (g), production rate (kg/m3), specific growth rate (SGR % day?1). The best final mean body weight (g), specific growth rate (SGR % day?1), and production rate (kg/m3) were recorded in groups of fish fed with feeding frequency four times daily. Whole fish moisture, protein, fat, and ash contents were significantly influenced (P ≤ 0.05) by protein sources and feeding frequency, except protein not influenced with feeding frequency. Energy was significantly (P < 0.05) influenced by feeding frequency, but not by dietary protein sources. Economic evaluation indicated that soybean meal (Diet B) at four times feeding daily was the most cost-effective and affordable feed strategy for farmers. We conclude that a soybean diet fed four times daily is recommended for adult Nile tilapia reared in concrete tanks.  相似文献   

19.
Two trials were designed to quantify the effect of feeding ratio and fish size on the cohabitation transmission of Loma salmonae, the causative agent of microsporidial gill disease (MGD) in salmonids, Oncorhynchus spp. To evaluate the effect of feeding ratio on disease onset, groups of 45 rainbow trout, O. mykiss (Walbaum) (RBT), were fed daily at 1% (low), 2% (medium) or 4% (high) of the fish biomass in the tank. There were three tanks at each feeding level: two tanks were exposed to the pathogen and one was a control. For the second objective, 300 RBT were separated into seven tanks so that the weight classifications were small (17-23 g), medium (32-38 g) and large (57-63 g). Each size class was done in duplicate with one control tank containing medium-sized fish. Separately for each trial, on day 0 post-exposure (PE) five highly infectious RBT were added to each tank (not including the control tanks) to begin the cohabitation exposure period. Beginning on day 21 PE and continuing biweekly until days 70 and 77 PE for the feeding and fish size trials, respectively, each fish was evaluated for visible branchial xenomas to determine disease onset time. Using survival analysis, the survival curves for the low, medium and high feedings were not significantly different from each other. However, there were significant differences amongst the small, medium and large weight classes in the size trial. The median numbers of days to the development of branchial xenomas was 31, 38 and 42 for small, medium and large size fish, respectively. On any given day, a medium or large sized fish had a hazard ratio for developing branchial xenomas of 0.66 and 0.63, respectively, compared with a small fish. In addition to host species and host strain differences, fish size is now considered a host risk factor for the development of MGD.  相似文献   

20.
The present work was designed to evaluate the effects of various feeding regimens on rabbitfish growth and condition. Twelve juvenile rabbitfish Siganus rivulatus (7.3 ± 0.1 g) were stocked into each of 15 tanks. Tanks were randomly assigned one of five treatments with three replicate tanks per treatment. Treatments were G‐I: fish fed once daily at 08.00; G‐II: fish fed once daily at 17.00; G‐III: fish fed twice daily at 08.00, 17.00; G‐IV: fish fed three times daily, at 08.00, 13.00, 17.00; G‐V: fish fed three times daily at 08.00, 13.00, 17.00 for six consecutive days, followed by 1 day of fasting. Fish were offered a commercial diet (Golden Extruded, 450 g kg?1 protein, 200 g kg?1 lipids) to apparent satiation. At the conclusion of the study, weight gain of rabbitfish fed three times daily (273.1%) was significantly greater than weight gain of fish in all other treatments. Feed conversion ratio (FCR) of fish fed once per day (1.5) was significantly greater than FCR in all other treatments. Proportion of lipids in fish fed three times per day was significantly greater than in fish from other treatments. Ultrastructure of muscle of fish offered feed three times daily had a better organized appearance and better defined striation than muscle of fish in other treatments. Accordingly, feeding rabbitfish three times daily is better than feeding them once or twice daily and also improves muscle ultrastructure and quality.  相似文献   

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