Darkbarbel Catfish Research Articles

Conjugated linoleic acid alters growth performance, tissue lipid deposition, and fatty acid composition of darkbarbel catfish (Pelteobagrus vachelli).

Fatty liver syndrome is a prevalent problem of farmed fish. Conjugated linoleic acid (CLA) has received increased attention recently as a fat-reducing fatty acid to control fat deposition in mammals. Therefore, the aim of the present study was to determine whether dietary CLA can reduce tissue lipid content of darkbarbel catfish (Pelteobagrus vachelli) and whether decreased lipid content is partially due to alterations in lipid metabolism enzyme activities and fatty acid profiles. A 76-day feeding trial was conducted to investigate the effect of dietary CLA on the growth, tissue lipid deposition, and fatty acid composition of darkbarbel catfish. Five diets containing 0 % (control), 0.5 % (CLA0.5), 1 % (CLA1), 2 % (CLA2), and 3 % (CLA3) CLA levels were evaluated. Results showed that fish fed with 2-3 % CLA diets showed a significantly lower specific growth rate and feed conversion efficiency than those fed with the control diet. Dietary CLA decreased the lipid contents in the liver and intraperitoneal fat with the CLA levels from 1 to 3 %. Fish fed with 2-3 % CLA diets showed significantly higher lipoprotein lipase and hepatic triacylglycerol lipase activities in liver than those of fish fed with the control, and fish fed with 1-3 % CLA diets had significantly higher pancreatic triacylglycerol lipase activities in liver than those of fish fed with the control. Dietary CLA was incorporated into liver, intraperitoneal fat, and muscle lipids, with higher percentages observed in liver compared with other tissues. Liver CLA deposition was at the expense of monounsaturated fatty acids (MUFA). In contrast, CLA deposition appeared to be primarily at the expense of MUFA and n-3 polyunsaturated fatty acids (PUFA) in the intraperitoneal fat, whereas in muscle it was at the expense of n-3 PUFA. Our results suggested that CLA at a 1 % dose can reduce liver lipid content without eliciting any negative effect on growth rate in darkbarbel catfish. This lipid-lowering effect could be in part due to an increment in the activity of lipid metabolism enzymes and an extensive interconversion of fatty acids. Although CLA deposition in muscle (0.66-3.19 % of total fatty acids) are higher than presented in natural sources of CLA, EPA (C20:5n-3) in fish muscle appears simultaneously expendable, when the fish fed with 2-3 % CLA.

Effects of ammonia stress, dietary linseed oil and Edwardsiella ictaluri challenge on juvenile darkbarbel catfish Pelteobagrus vachelli

A two-stage study was carried out to test the response of juvenile darkbarbel catfish Pelteobagrus vachelli to ammonia stress, dietary lipid and bacterial challenge. At stage 1, the catfish (0.99 ± 0.01 g) fed a commercial diet were exposed to 0.01 and 5.70 mg L−1 total ammonia nitrogen in nine replicates for 14 days. At stage 2, all fish previously exposed to either low or high ammonia were separately transferred into low ammonia (<0.01 mg L−1), and divided into three feeding groups. Fish were then fed three levels of linseed oil (0, 2 and 4%) in triplicate for 46 days. Fish growth performance and immune response were low in high ammonia at stage 1. At stage 2, fish growth and immune response were not significantly different between fish previously exposed to low and high ammonia in all diets. Fish fed 4% linseed oil showed the greatest weight gain, feed efficiency ratio, red blood cells, hemoglobin and hematocrit, and achieved higher lysozyme activity, phagocytic index, respiratory burst and total immunoglobulin than fish fed 0% linseed oil, but did not differ from fish fed 2% linseed oil regardless of previous ammonia exposure. After 14-day infection of Edwardsiella ictaluri, cumulative mortality of fish previously exposed to low ammonia was lower than that of fish exposed to high ammonia in all diets. Cumulative mortality of fish fed 0% linseed oil was highest, but the antibody titer of fish fed 4% linseed oil was highest regardless of previous ammonia treatments. This study indicates that ammonia stress has a lasting effect even after ammonia is lowed, but the adverse effect on fish can be mitigated through manipulation of dietary oil inclusion, especially under the challenge of pathogenic bacteria.

Effects of Dietary Soy Protein Concentrate on Growth Performance, Digestion, and Protein Metabolism of Juvenile Darkbarbel Catfish Pelteobagrus vachelli

A 10-week feeding trial in a recirculation rearing system was conducted to investigate the effects of dietary soy protein concentrate (SPC) levels on survival, growth, digestion, and protein metabolism of juvenile darkbarbel catfish Pelteobagrus vachelli. The results demonstrated that survival and whole-body composition were independent of dietary treatments. Feed intake (FI), specific growth rate (SGR), feed conversion ratio (FCR), apparent digestibility coefficients, digestive enzymes (pepsin and trypsin) activity and protein metabolism enzymes (alanine aminotransferases) decreased with increasing dietary SPC. The diet with 60% SPC was least cost effective. Results suggest that SPC could replace 60% or less fish meal protein without negatively influencing the growth of juvenile Pelteobagrus vachelli.

Growth, immune response and resistance toAeromonas hydrophilaof darkbarbel catfish, Pelteobagrus vachelli(Richardson), fed diets with different linolenic acid levels

Experimental diets were formulated containing six levels of linolenic acid (0%, 0.5%, 1.0%, 1.5%, 2.0% and 2.5%) and each diet was fed to darkbarbel catfish Pelteobagrus vachelli in triplicate for 84 days. Weight gain, specific growth rate and feed efficiency increased with the increasing levels of dietary linolenic acid, but were not significantly different among diets containing 1.0%, 1.5%, 2.0% and 2.5% linolenic acid. Red blood cell count and haemoglobin were significantly higher in fish fed the 1.0% linolenic acid than other diets. Lysozyme activity and immunoglobulin M content in fish fed 1.0% of linolenic acid were significantly higher compared with the other diets. Antibody titre in fish fed 1.0–2.5% linolenic acids was significantly higher than in fish fed 0 or 0.5% linolenic acid 14 days after Aeromonas hydrophila challenge. This study indicates that linolenic acid is essential to darkbarbel catfish. Two-straight broken-line analysis with SGR showed that a dietary level of 1.29% linolenic acid is the minimum required for adequate growth of darkbarbel catfish. Considering other measured indicators of fish performance, a level of 1.0–1.5% linolenic acid in the diet is recommended for the darkbarbel catfish.

Growth performance, antioxidant status and immune response in darkbarbel catfish Pelteobagrus vachelli fed different PUFA/vitamin E dietary levels and exposed to high or low ammonia

Triplicate groups of juvenile darkbarbel catfish (0.99±0.01g) were fed three levels of linseed oil (2, 4 and 6%) rich in polyunsaturated fatty acids (PUFAs) and three levels of vitamin E (50, 200 and 400mg/kg diet) for 60days under two ammonia concentrations (0.01 and 5.70mg/L total ammonia nitrogen, TA-N). Growth performance, immune response and pathogen resistance of fish were higher in fish under low ammonia conditions. Under high ammonia, fish fed 400mg/kg vitamin E showed higher growth performance and immune response. Blood status and immune responses were improved in fish fed 6% linseed oil. However, fish fed 2% linseed oil or 400mg/kg vitamin E showed a lower level of malondialdehyde regardless of ammonia levels. After 14days infection of Edwardsiella ictaluri, cumulative mortality was lowest when fish were exposed to high ammonia and fed on 4–6% linseed oil. Fish fed 6% linseed oil or 400mg/kg vitamin E yielded a higher level of antibody titer regardless of ammonia addition. This study indicates that the harmful effects of ammonia on fish can be mitigated when fish are fed on 2% linseed oil and 400mg/kg vitamin E.

English

An 80 day feeding trial was conducted to evaluate the effects of dietary inclusion of soybean oil to replace fish oil in the diet on growth, muscle fatty acids and immune responses of Pelteobagrus vachelli. Isonitrogenous and isocaloric diets were formulated with four fish oil to soybean oil ratios at 8:0 (FO, control), 6:2 (MO1), 2:6(MO2) and 0:8 (SO) in triplicate. Each diet was fed to juvenile darkbarbel catfish (1.0 ± 0.02 g) twice daily. No significant differences were found in weight gain, special growth rate, hepatosomatic index and intraperitoneal fat ratio among all the treatments. Incorporation of soybean oil significantly modified the fatty acid composition and n-3 and n-6 PUFAs ratio in muscle of fish. Fish fed MO1 showed significantly higher serum lysozyme activity, complement C3 and C4 contents and total IgM content than those fed other diets. These results indicate that partial replacement of fish oil with soybean oil does not compromise fish growth, but improve fish immunity. This study suggests that 25% fish oil replacement with soybean oil can be used in the practical diet of this fish. Key words: Darkbarbel catfish, Pelteobagrus vachelli, soybean oil, growth, fatty acid composition, immune responses.

Comparative effects of dietary supplementation with maggot meal and soybean meal in gibel carp (Carassius auratus gibelio) and darkbarbel catfish (Pelteobagrus vachelli): growth performance and antioxidant responses

A 6-week growth trial was conducted to investigate the effect of dietary supplementation with maggot meal (MGM) and soybean meal (SBM) on the growth performance and antioxidant responses of gibel carp (GC) and darkbarbel catfish (DC). The basal diet was formulated to contain 114 g kg−1 fish meal (FM) and 200 g kg−1 SBM. The basal diet was supplemented with either 280 g kg−1 FM (Control), 390 g kg−1 MGM or 450 g kg−1 SBM to obtain three isonitrogenous (crude protein: 380 g kg−1) and isocaloric (gross energy: 16 kJ g−1) diets. For GC, a significant decrease in specific growth rate (SGR) was only observed in fish fed the SBM diet compared with the control (P < 0.05). Principal components analysis (PCA) of GC showed a higher similarity in antioxidant response to dietary supplementation with MGM and SBM proteins between liver and intestine, but the DC did not. The present results suggest that supplementing 390 g kg−1 MGM protein to basal diet cause an enhancement of the antioxidant capacity in GC, but supplementing 390 g kg−1 MGM and 450 g kg−1 SBM proteins to basal diets resulted in a significant attenuation of the antioxidant capacity in DC.

Effects of dietary arginine and lysine on growth and non-specific immune responses of juvenile darkbarbel catfish(&lt;I&gt;Pelteobagrus vachelli&lt;/I&gt;)

Effects of dietary arginine and lysine on growth and non-specific immune responses of juvenile darkbarbel catfish(&lt;I&gt;Pelteobagrus vachelli&lt;/I&gt;)

Cloning and differential expression pattern of pituitary adenylyl cyclase-activating polypeptide and the PACAP-specific receptor in darkbarbel catfish Pelteobagrus vachelli

Pituitary adenylyl cyclase-activating polypeptide (PACAP) can mediate growth hormone and gonadotropin release in teleost pituitary via PACAP receptors. In this study, the full-length cDNAs encoding PACAP and PACAP-related peptide (PRP) and the PACAP-specific receptor (PAC1-R) were cloned from the brain of darkbarbel catfish Pelteobagrus vachelli. The PRP-PACAP cDNA had two variants expressed by alternative splicing: a long form encoding both PRP and PACAP and a short form encoding PACAP only. Our data showed that the exon skipping on the PACAP transcripts was a possible mechanism regulating the expression ratio of PACAP to PRP in non-mammalian vertebrates. Based on multi-sequence alignments and phylogenetic analysis, the catfish PACAP and PAC1-R were highly conserved during evolution. Real-time quantitative PCR revealed that the PACAP-short and PAC1-R tanscripts were mainly expressed in the brain and gonad of darkbarbel catfish, though a small amount of mRNAs was also found in other tissues. Immunofluorescent staining studies showed wide distribution and high levels of PAC1-R in the catfish brain, suggesting that the PAC1-R form may play a central role in growth hormone release. The expressions of PACAP and PAC1-R in gonads and the occurrence of PACAP-immunoreactive material in testis suggest that PACAP may act as a paracrine/autocrine factor for gonad development.

Effects of melamine on growth performance and skin color of darkbarbel catfish ( Pelteobagrus vachelli)

A feeding experiment was conducted to investigate the effects of melamine (MEL) on growth performance and skin color of darkbarbel catfish ( Pelteobagrus vachelli). Artificial diets with 0.2, 0.5 and 1% MEL supplementation were fed to juvenile darkbarbel catfish (initial weight 14.30 ± 0.10 g) for eight weeks, and MEL-nonsupplemented diet was used as a control. The results indicated that specific growth rate (SGR) of darkbarbel catfish fed the diets with MEL supplementation was significantly lower than that of the control group ( P < 0.05). Melanin content in dorsal skin decreased with increasing MEL supplementation. Dorsal skin melanin content of darkbarbel catfish fed the diets with 0.5 and 1% MEL supplementation was significantly lower than that of the control group ( P < 0.05). Lightness (CIE [1976], L* tristimuli value) of dorsal skin increased with increasing supplementation of MEL. L* of darkbarbel catfish fed the diet with 0.5% and 1% MEL was significantly higher than the control group ( P < 0.05). However, tyrosinase activity of dorsal skin was not significantly affected by dietary MEL ( P > 0.05). These results indicated that dietary MEL could decrease melanin content of darkbarbel catfish dorsal skin, and therefore increase its lightness. During this procedure, tyrosinase activity of dorsal skin was not significantly affected.

Decreased trophic position as a function of increasing body size of a benthic omnivorous fish from the largest freshwater lake in China

Potential body size-trophic position relationships of the Darkbarbel catfish Pelteobagrus vachelli (Richardson 1846) were examined using stable isotope analysis. Pelteobagrus vachelli is a benthic feeding fish from Lake Poyang, the largest freshwater lake in China. Two-source mixing model with mussel (Corbicula fluminea) and snail (Bellamya aeruginosa) as baseline primary consumers of planktonic and benthic food webs, respectively, was used to estimate contribution of carbon derived from planktonic vs. benthic food web. Results showed that as an indicator of trophic position, delta(15)N was negatively correlated with the body length and weight of the fish; on the other hand, as an indicator of the end-member food sources, delta(13)C was not correlated with fish size. The mixing model results showed that the averaged trophic position of our sampled 3.3-12.7 cm Pelteobagrus vachelli was 3.1 +/- 0.2 and derived 68 +/- 27% of their food from the benthic food web, confirming that the feeding behavior of the catfish favors benthic food sources.

COMPARATIVE STUDY ABOUT FLESH CONTENTS AND NUTRIENT VALUES IN BROWN BULLHEAD, LOACH AND DARKBARBEL CATFISH

Three aquaculture species, brown bullhead (Ictalurus ncbulosus), loach (Misgurnus anguillicaudatus) and Darkbarbel catfish (Pelteobagrus fulvidraco, Richardson), were studied for flesh contents, processing characteristics and nutritional composition of fish muscles. The results showed that flesh contents of brown bullhead (74.48±2.01)% and Darkbarbel catfish (73.63±3.29)% were significantly higher than that of loach (65.95±1.27)%. The cooked meat rate of loach (69.36±2.35)% was higher than that of other two species. Protein content of muscles in loach (16.24±0.56)% was significant higher than that in brown bullhead (15.34±0.44)% and Darkbarbel catfish (14.45±0.24)%. Fat content of muscles in Darkbarbel catfish (2.41±0.17)% was significant higher than that in brown bullhead (1.22±0.33)% and loach (1.26±0.60)%. The proportion of inclusive essential amino acids for human in muscle total amino acids of brown bull-head, loach and Darkbarbel catfish were (40.06±0.63)%, (39.79±0.57)% and (40.36±0.52)%, respectively. Valine was first limited amino acid in muscle of the three species of fish and the F value was between 4.90-5.06. In three species, the delicious amino acid contents of muscles were more than 29%. The unsaturated fatty acid contents of muscles were significant higher than those of saturated fatty acids. The content of 20:5ω-3 fatty acid (EPA) in muscles of brown bull-head (2.52±0.30)% was significant higher than that of loach (0.16±0.05)% and Darkbarbel catfish (0.12±0.04)%, but the contents of 22:6ω-3 (DHA) in muscles of loach (4.62±0.30)% and Darkbarbel catfish (2.86±0.32)% were significantly higher than that of brown bullhead (1.84±0.27)%. The results indicated that loach and Darkbarbel catfish are delicious and these three fish are nutrient aquatic food for human being.

Effects of stocking density on growth and skin color of juvenile darkbarbel catfish Pelteobagrus vachelli (Richardson)

A 3-month experiment was conducted to investigate the effects of stocking density on growth performance and skin color of juvenile darkbarbel catfish. Experimental fish (5.0 +/- 0.6 g; n = 160) were stocked in triplicate in 2 m(2) concrete tanks in a greenhouse at the initial density of 50, 150, 400 and 650 fish m(-2), respectively (0.42, 1.25, 3.33 and 5.42 kg m(-3)). At the end of the experiment, 60 fish from each tank were sampled to record body weight and total length, and six fish from each tank were sampled to measure skin color by instrumental color analysis. Results showed that stocking density affected growth performance significantly (P < 0.05). Final mean weight (W), final mean total length (L) and specific growth rate (SGR) were significantly higher at 150 fish m(-2) treatment and lower in both the highest and lowest (650 and 50 fish m(-2)) density treatments (P < 0.05). The condition factor (CF) was higher in 150 and 50 fish m(-2) and lowest at 650 fish m(-2) treatment; the coefficient of variation of weight (CV) tended to increase with the increase in stocking density, which was lowest in 50 fish m(-2) and highest in 650 fish m(-2). Stocking density also affected the skin color parameters, L* (lightness), a* (redness), b* (yellowness) and h* (hue), significantly (P < 0.05). The values of these parameters tended to decline with the increase in stocking density. Results of the present study suggest that growth performance and skin color responses to stock density exhibit different patterns for darkbarbel catfish juveniles: highest and lowest densities impaired growth rate, and higher density had a darkening effect on skin color.

The effect of exercise training on the metabolic interaction between digestion and locomotion in juvenile darkbarbel catfish ( Peltebagrus vachelli)

To examine the effects of exercise training on the metabolic interaction between digestion and locomotion in juvenile darkbarbel catfish ( Peltebagrus vachelli) (5.58 ± 0.04 g), the postprandial metabolic response, critical swimming speeds ( U crit) and oxygen consumption rates ( VO 2) during swimming were measured on fish held at a constant temperature (25 °C). Fish were fed a diet of cutlets of freshly killed loach. Fish in the trained group were forced to swim at 60% U crit for 50 min followed by an exhaustive 10-min chase once daily for 21 days. Exercise training did not produce significant differences in resting VO 2 ( VO 2rest) and postprandial peak VO 2 ( VO 2peak) compared to the non-trained groups. However, exercise training elicited a significant decrease in both the duration and energy expenditure of digestion when fed with similar food ( P < 0.05). Feeding had no significant effect on U crit of non-trained fish, while it caused a significantly lower U crit (compared to fasting fish) in trained fish ( P < 0.05). Training resulted in a significantly higher U crit and active VO 2 ( VO 2active) in fasting fish when fish swam at U crit. However, training had no effect on either the U crit or VO 2active of post-feeding fish. Our results suggest that: (1) the central cardio-respiratory systems of non-trained darkbarbel catfish can support the oxygen demands of both digestion and the locomotion simultaneously; (2) the metabolic mode of competition in darkbarbel catfish is flexible; it changed from an additive model to a digestion-priority model after exercise training; (3) training may be accounted for cardio-respiratory capacity increase and following improvement of swimming performance during fasting in darkbarbel catfish, although, the swimming capacity was sacrificed to digestion in the situation of postprandial locomotion.

Effects of dietary lipid levels on growth, survival and lipid metabolism during early ontogeny of Pelteobagrus vachelli larvae

A feeding trial was conducted to investigate the effect of dietary lipid level on darkbarbel catfish ( Pelteobagrus vachelli) larvae during ontogeny with regard to growth, survival and lipid utilization. Larvae were fed, from mouth opening to 20 days after hatching (DAH), with five isonitrogenous microdiets containing different lipid levels (58, 74, 111, 151 and 199 g kg − 1 diet). Live prey (newly hatched Artemia, unenriched) was used as the control diet. The activities of lipoprotein lipase (LPL), hepatic lipase (HL), pancreatic lipase (PL) and LPL gene expression at 3 DAH (mouth opening), 6 DAH, 11 DAH and 20 DAH were examined. The results showed that dietary lipid significantly affected survival and growth of darkbarbel catfish larvae. At the end of the feeding trial, larvae fed diets containing 111 to 151 g lipid kg − 1 had significantly higher survival. Specific growth rate (SGR) of larvae fed the diet containing the highest dietary lipid (199 g kg − 1 ) was significantly ( P < 0.05) lower while no significant differences were observed among other groups fed formulated diets. LPL mRNA level generally increased first with increasing dietary lipid levels and then reached a plateau at different sampling ages. A similar pattern was observed for LPL activity only at 6 DAH and 20 DAH. High dietary lipid increased HL activity at 20 DAH. At 6 DAH, highest PL activity was observed at 199 g lipid kg − 1 diet. Higher dietary lipid resulted in earlier elevated activities of LPL, PL and HL. The specific activities of the above three enzymes and LPL mRNA expression were detected at mouth opening and were significantly influenced by age. The activities of these enzymes increased first and then decreased or reached a plateau during development. The results suggest that dietary lipid could modify lipid utilization during ontogeny of darkbarbel catfish larvae.

The behavioural, digestive and metabolic characteristics of fishes with different foraging strategies

To test the hypothesis that digestion has a more notable physiological effect on ambush foragers than on active foragers, we investigated the behavioural, digestive and metabolic characteristics, as well as the postprandial locomotory capacity, of four species of juvenile fish distributed along the Yangtze River, China, with distinct foraging strategies. The ambush foraging southern catfish (Silurus meridionlis) had the fewest movements per minute (MPM), lowest per cent time spent moving (PTM), slowest critical swimming speed (Ucrit), lowest maintenance metabolism (VO2rest) and lowest maximum locomotory metabolism (VO2max)). However, the southern catfish had the highest feeding level and maximum feeding metabolism (VO2peak) and the greatest decrease in Ucrit after consumption of a large meal. Thus, this fish is highly adapted to its ambush behavioural strategy and sedentary life style. In the herbivorous grass carp (Ctenopharyngodon idellus), a low digestive capacity led to little change in postprandial locomotory performance, which benefits its frequent grazing behaviour. In this species, the greater amount of energy spent on routine activity and avoiding predators versus Ucrit might be related to its herbivorous life style and high predation risk. The active foraging crucian carp (Carassius auratus) adopts a unique high energy cost strategy that allows for high capacity in both routine activity and digestion, and the great flexibility of its cardio-respiratory capacity (increased VO2max after feeding) guarantees a small decrease in Ucrit even after maximum feeding. Finally, the sluggish foraging darkbarbel catfish (Pelteobagrus vachelli) has low digestive and locomotory capacity, but its energy-efficient venomous defence strategy may be related to its abundance. These results show that the digestive, behavioural and metabolic strategies differ among these fish species. The locomotory capacity in the sedentary fishes decreased profoundly after feeding, whereas it decreased little or not at all in the active fishes. The maintenance of high locomotory capacity after eating in the active fishes is probably related to a large metabolic capacity, a lower digestive capacity or an improvement in cardio-respiratory capacity after feeding.

The effect of exhaustive chasing training and detraining on swimming performance in juvenile darkbarbel catfish (Peltebagrus vachelli)

To investigate the effects of exhaustive chasing training and detraining on the swimming performance of juvenile darkbarbel catfish (Peltebagrus vachelli Richardson), we performed exhaustive chasing training daily for 14 days and subsequently detrained fish for 7 days. Chasing training resulted in significant increases in critical swimming speed (U (crit)), post-chasing peak oxygen consumption rate (VO(2 peak)), and heart and gill indexes compared with non-trained controls. Both resting oxygen consumption (VO(2 rest)) and excess post-chasing VO(2) (EPOC) were unaffected by exhaustive chasing training. Fish that underwent chasing training had lower levels of whole-body lipid content and reduced food intake and growth compared with non-trained control fish; however, condition factor was not affected by chasing training. Seven days of detraining reversed the effects of exhaustive chasing training. Overall, these data suggested that short-term exhaustive chasing training improves aerobic swimming capacity in darkbarbel catfish, but the training effects are reversible over a short period of time.

Effect of meal size on excess post-exercise oxygen consumption in fishes with different locomotive and digestive performance

Effects of feeding on pre-exercise VO(2) and excess post-exercise oxygen consumption (EPOC) after exhaustive exercise were investigated in sedentary southern catfish, active herbivorous grass carp, omnivorous crucian carp, and sluggish omnivorous darkbarbel catfish to test whether feeding had different effects on EPOC and to compare EPOC in fishes with different ecological habits. For fasting fish, the pre-exercise and peak post-exercise VO(2) were higher and recovery rates were faster in crucian carp and grass carp compared to those of darkbarbel catfish and southern catfish. EPOC magnitudes of grass carp and southern catfish were significantly larger than those of crucian carp and darkbarbel catfish. Feeding had no significant effect on peak post-exercise VO(2), recovery rate, and EPOC magnitude in grass carp. Both the pre-exercise and peak post-exercise VO(2) increased with meal size, while the EPOC magnitude and duration decreased significantly in the larger meal size groups of crucian carp and southern catfish. In darkbarbel catfish, both the pre-exercise and peak post-exercise VO(2) increased with meal size, but the VO(2) increment elicited by exercise was larger in feeding groups compared with the fasting group. These results suggest that (1) the characteristics of the post-exercise VO(2) profile, such as peak post-exercise VO(2) and recovery rate, were closely related to the activity of fishes, whereas the EPOC magnitude was not and (2) the effects of feeding on EPOC were more closely related to the postprandial increase in VO(2).