Simultaneous effects of nutritional and environmental factors on growth and flesh quality of Perca fluviatilis using a fractional factorial design study

Fractional factorial design is a practical approach for studying multiple factors, with a minimum of experimental units. The objective of this work was to study the simultaneous effects of nutritional and environmental factors on both growth and flesh quality of common perch (Perca fluviatilis), a new inland aquaculture species. This study sought answering the two following questions: (i) which combinations of factors allow improving growth, food efficiency, and technological, sensorial and nutritional qualities? (ii) is it possible to simultaneously improve growth performances and flesh quality? In a first experiment, twelve factors (7 nutritional and 5 environmental factors) were each tested at 2 levels in a fractional factorial design in 24 independent recirculating 500 L tanks. The best 4 combinations identified in this first experiment were then validated in a second experiment. The first phase of the multifactorial approach used here allowed revealing emergent information: i) there is a combination of factors that allows reducing both the heterogeneity of the production and the losses of nitrates and phosphates, while preserving good characteristics of growth and quality of fillets; ii) it is possible to improve the quality of the aquatic production system, without decreasing significantly growth efficiency; iii) the effect of a given factor, even such an important one like diet, temperature or target biomass, depends on the levels of the other rearing factor levels, thus the usual reference optimum used for a given factor has no meaning theoretically and can be questioned according to the levels of the other factors which act altogether on the functioning of the rearing system.The input factor combinations resulting in a significant enhancement of single output variables or several output variables were identified (e.g. improvement of feed efficiency, and/or fillet docosahexanoic acid content). Our results clearly demonstrate a strong interdependence of input factors into the animal rearing system, particularly between nutritional and environmental ones.     

A factorial approach to defining the energy and protein requirements of Tra Catfish,Pangasianodon hypothalamus

This study assessed the protein and energy requirements of Tra catfish (Pangasianodon hypothalamus) using a bio‐energetic factorial approach. To examine these parameters, a series of inter‐related studies were undertaken to define the various factorial parameters. Studies included controlled laboratory experiments and field‐data collection from commercial farms in the Mekong Delta region of Vietnam. Key components of the model include parameters for maintenance energy (39.7 kJ kg^?0.844 day^?1 at 32 °C) and protein (0.467 g kg^?0.833 day^?1 at 32 °C) demands, the effect of animal live‐weight and temperature on growth and maintenance energy demands, the efficiencies of energy and protein utilization at various energy and protein intake levels and the variability in whole body composition with varying live‐weight. Interestingly, both the energy [0.510· (Energy intake) ? 11.143] and protein [0.322·(Protein intake) + 0.665] utilization efficiencies at near satiety feed intake levels were substantially lower than that observed from other fish species. Modelling using these equations was used to iteratively derive optimal diet designs and feeding rations for growing Pangasius catfish.     

Effect of dietary carbohydrates and lipids on growth in cachama (Piaractus brachypomus)

The effects of diets with three contents of carbohydrates and lipids were evaluated on the growing performance of cachama Piaractus brachypomus juveniles (initial weight 7.8 ± 0.49 g). The experiments were performed a 3 × 3 factorial design (200, 280 and 360 g of carbohydrates and 40, 80 and 120 g of lipids kg^?1). Protein content was kept constant in 320 g kg^?1 and digestible energy between 11.3 and 16.1 MJ kg^?1. Simple effects and interaction of factors on growth performance varied significantly (P < 0.05) indicating dependence among them. The maximum weight gain was observed in fish fed 200 and 280 g kg^?1 carbohydrates and 40 g kg^?1 lipids. Increase of lipids from 80 to 120 g kg^?1 reduced growth significantly. Protein efficiency rate and percentages of protein retention and energy were positively correlated with carbohydrate levels and no significant differences (P > 0.05) were observed with the lipid levels. Results indicate that cachama utilizes carbohydrates as energy source more efficiently than lipids; likewise, lipid levels over 40 g kg^?1 depress growth at any carbohydrates level.     

Combined effects of salinity and potassium concentration on juvenile mulloway (Argyrosomus japonicus, Temminck and Schlegel) in inland saline groundwater

This paper reports on experiments conducted to examine the combined effects of salinity and potassium concentration on survival and growth of juvenile mulloway (Argyrosomus japonicus, Temminck and Schlegel) in inland saline groundwater. Three separate experiments were conducted in 20 (±1)°C water. In the first experiment, mulloway were held in 60 L aquaria (triplicate) with salinities of 5, 15, 25 or 35 g L^?1 and potassium concentrations of 20%, 40%, 60% or 80% of the concentration present in oceanic water of the equivalent salinity in a 4 × 4 factorial combination for 7 days. Response surface contour diagrams were generated from survival data to estimate optimal conditions. The results showed that maximum survival of juvenile mulloway occurred at salinities of >14 g L^?1 and potassium concentrations of >38%. Survival was lowest at salinities of <7 and >33 g L^?1 and potassium concentrations of <25%. The second experiment was conducted with mulloway held in 60 L aquaria at salinities of 15, 25 or 35 g L^?1 and potassium concentrations of 40%, 60%, 80% or 100% in a 3 × 4 factorial combination for 44 days. Optimal conditions for maximum survival and growth of mulloway were within a salinity range of 15–35 g L^?1 and potassium concentration above 40%. The third experiment was conducted in three 500 L tanks to record the survival and growth of mulloway fingerlings held at 20 (±1)°C, 23 g L^?1 salinity and potassium concentrations of 50% for 8 months. Survival and growth of mulloway fingerling in inland saline groundwater were similar to those reported from a semi‐intensive floating tank system in inland saline water and sea cage trials in oceanic water.     

Dietary protein requirement of juvenile Mexican Silverside (Menidia estor Jordan 1879), a stomachless zooplanktophagous fish

A study was conducted in order to determine the protein requirements of juvenile Mexican silverside (Menidia estor). Seven isoenergetic diets (≈19.9 MJ kg⁻¹) with dietary protein levels of 250, 300, 350, 400, 450, 500 and 550 g kg⁻¹ were prepared as flakes using jack (Caranx sp.) and red snapper (Lutjanus sp.) fillets, tuna (Thunnus sp.) ovaries and California squid (Loligo sp.) as protein sources, and their effects on growth, survival and feed utilization of juvenile M. estor (69.24 ± 5.03 mg initial weight) were evaluated. Fish were fed by hand to apparent satiation, five times a day, for 8 weeks. Best growth and survival were obtained with diets with protein levels between 400 and 500 g kg⁻¹, with no significant differences between them (P > 0.05). Specific growth rate and feed intake were also highest for these treatments (P < 0.05). There were no significant differences in feed conversion ratio and protein efficiency ratio between fish fed all the diets. Broken‐line analysis of individual weight gain against protein level showed a protein requirement of 409 g kg⁻¹ for juveniles of M. estor.     

Combined effect of dietary protein and phytase levels on growth performance,feed utilization,and nutrients digestibility of African catfish,Clarias gariepinus (B.), reared in earthen ponds

The present study was based on a 2 × 4 factorial design with two levels of dietary protein (33% or 37% CP) and four phytase levels (0.0, 750, 1,000, and 1,250 FTU/kg diet). African catfish, Clarias gariepinus (B.) (10.7 ± 0.4 g), were distributed into earthen ponds (100 m² surface area per each) at a density of 4.5 fish per m². Fish were fed on the experimental diets up to satiation twice a day for 3 months. Another experiment with the same treatments was conducted in 45-L tanks for 2 months to evaluate nutrient retention and digestibility. The growth and production of African catfish fed phytase-enriched diets were higher than those fed the control diet. The highest fish performance and production was observed with fish fed 37% CP enriched with a 1,200 FTU/kg diet of phytase. Feed intake was significantly affected by supplemental phytase alone, where it increased significantly as dietary phytase increased at both protein levels, resulting in similar FCR values (1.31–1.46). Additionally, the maximum values of protein efficiency ratio, protein retention, and phosphorus retention were obtained at 33% CP with phytase levels of 750–1,000 FTU/kg diet. It is also noticed that organic matter, protein, and phosphorus were more digestible in fish fed a 37% CP diet with high phytase levels. These results suggest that the optimum performance and production of African catfish were observed at a 37.0% CP diet enriched with a phytase level of 1,200 FTU/kg diet.     

Effect of two choline sources on the performance of postlarval Marsupenaeus japonicus bate

The present study was conducted to clarify the effect and the interaction between two choline sources [choline chloride (CC) and soybean phosphatidylcholine (SPC)] on the performances of postlarval shrimp, Marsupenaeus japonicus. A 30‐day feeding experiment was conducted as a 2 × 2 factorial design. The postlarval shrimp were fed with four κ‐carrageenan micro‐bound diets that contained two levels of CC (0.6 and 1.2 g kg⁻¹) and two levels of SPC (20 and 40 g kg⁻¹). A significant (P < 0.05) interaction was also detected between both choline sources in terms of the weight gain, apparent feed efficiency ratio, apparent protein efficiency ratio and total lipid, free choline and phosphatidylcholine contents of the shrimp whole body except for survival, moisture, and protein contents of the whole body. At the lower dietary SPC (20 g kg⁻¹) level, increasing of CC level from 0.6 to 1.2 g kg⁻¹ significantly enhanced the above parameters, whereas such positive effect of dietary CC was diminished at the higher dietary SPC (40 g kg⁻¹) level. Standing on the different viewpoint, the effect of supplemental SPC was also affected with the dietary levels of CC.     

The administration of Lactobacillus plantarum directly to food: An effective way to improve the survival and growth of juvenile lined seahorses (Hippocampus erectus)

Previously, we found Lactobacillus plantarum had probiotic effects on lined seahorse (Hippocampus erectus) juveniles by the addition Lactobacillus directly into rearing seawater containing juveniles and their food (i.e. copepods). However, how the juveniles consumed Lactobacillus, directly from water or from copepods in whose guts Lactobacillus may have accumulated by ingestion, is still unclear. To clarify this, three experiments were successively carried out in this study. In the first experiment, the manner by which juveniles consumed Lactobacillus, namely, directly from food, was discovered via a 2 × 2 factorial design with two factors of water and food, and two levels with and without L. plantarum. In the second experiment, a 5 × 4 factorial design with five levels of L. plantarum doses (D: 5, 10, 20, 40 and 80 × 10⁸ cfu/L) and four levels of enrichment time (T: 0.5, 1.0, 1.5 and 2.0 hr) was conducted to analyse lactic acid bacteria (LAB) contents in the enriched copepods under different treatments. In the third experiment, six kinds of Lactobacillus‐enriched copepods chosen from the second experiment that carried significantly different LAB contents were fed to juveniles, and it was found that the copepods containing LAB greater than 5 log₁₀colonies/g had the most improved effects for survival and growth. In conclusion, the effective manner of L. plantarum administration in seahorses is by the addition to their food. Additionally, D40 * T1.0, whose LAB content was more than 5 log₁₀colonies/g, is generally the most economic copepod treatment for improving survival and growth in H. erectus rearing.     

Effects of water-soluble and fat-soluble choline sources on the performances of juvenile kuruma shrimp, Marsupenaeus japonicus Bate

The present study was undertaken to clarify the effect and interaction of choline chloride (CC) and phosphatidylcholine (PC), the water‐ and fat‐soluble sources of choline, on the performances of kuruma shrimp, Marsupenaeus japonicus juveniles using as response variables such as percent weight gain (%WG), specific growth rate (SGR), survival (SR%), feed efficiency ratio (FER), protein efficiency ratio (PER), proximate composition, fatty acids profile and free choline and PC contents in the whole body of kuruma shrimp. A 40‐day feeding trial was conducted as a 2 × 3 factorial experiment with six test diets containing three levels of CC (0.3, 0.6 and 1.2 g kg^?1) and two levels of soybean PC (SPC; 2 and 4 g kg^?1). Both of the choline sources (CC and SPC) showed a significant interaction (P<0.05) regarding all the evaluated response variables except for the proximate and fatty acid contents. Interestingly, there was a positive effect (P<0.05) of CC observed with increasing its level at the low level of SPC and vice versa. However, the magnitudes of the beneficial effect of CC in terms of the evaluated parameters were changed with the different dietary levels of SPC. Also, the inclusion of higher levels of SPC (4 g kg^?1) or CC (0.6 and 1.2 g kg^?1) diminished the effect of the other source.     

The control of floating macrophytes by grass carp in net cages: experiments in two tropical hydroelectric reservoirs

The efficiency of grass carp (Ctenopharyngodon idella Val.) for biological control of floating aquatic macrophytes in net cages was assessed in two eutrophic tropical hydroelectric reservoirs through experiments using three macrophyte species (Eichhornia crassipes, Pistia stratiotes and Salvinia auriculata). A total of twenty experiments were performed in these reservoirs with a duration period between 21 and 30 days, during distinct seasons of the year. Sets of experiments were conducted using the three macrophyte species simultaneously in both reservoirs, and additional experiments were performed in one reservoir involving the separate use of each species. All macrophytes demonstrated significant growth in the absence of fish with total per day biomass increase rate ranging from 0.06 to 17.00%. The presence of grass carp significantly reduced macrophyte biomass in both reservoirs independent of fish size, stocking rate and available cage space. In all seasons, grass carp grazing pressure was higher for S. auriculata and lower for P. stratiotes. The results show that grass carp in net cages was able to use aquatic macrophytes as the only food source, controlling massive plant growth (especially S. auriculata and E. crassipes). Fish cages, already implemented in several reservoirs in Brazil, are easily manageable units at relatively low cost. Thus, biocontrol of macrophytes using caged grass carp is proposed as an effective low‐budget ecotechnological tool to control consumable plants while avoiding the removal of desirable aquatic vegetation and the resultant impact on local fauna.     

Optimum digestible protein and energy levels and ratio for greater amberjack Seriola dumerili (Risso) fingerling

A study was conducted to determine optimum dietary digestible protein (DP) and digestible energy (DE) levels and DP DE⁻¹ ratio for growth of greater amberjack Seriola dumerili fingerlings. A 3 × 3 factorial design with duplication was used in this study. Nine experimental diets were formulated to contain three levels of crude protein (CP; 420, 470 and 530 g kg⁻¹) and three levels of crude lipid (CL; 130, 180 and 230 g kg⁻¹). Nine groups of fingerling (initial weight 51.8 g) were fed each experimental diet for 40 days. Final body weight, feed efficiency, specific growth rate and energy efficiency were significantly affected by dietary protein and lipid level. These parameters tended to improve with increasing dietary protein level. Conversely, an increase of lipid level negatively affected these parameters. High growth rate and feed efficiency were obtained from fish fed the diet containing 393 g kg⁻¹ DP and 14.2 MJ kg⁻¹ DE (27.7 g MJ⁻¹ DP DE⁻¹). The high DP DE⁻¹ (27.7 g MJ⁻¹) indicates that greater amberjack fingerling are highly dependent on dietary protein as an energy source.     

Assessment of diet and temperature on the overall performance of Patagonian red octopus (Enteroctopus megalocyathus,Gould) paralarvae

The limitation to sustain the Patagonian red octopus Enteroctopus megalocyathus aquaculture is the lack of an efficient diet to obtain high survival during the paralarvae stage. This work has studied the performance of paralarvae under different combinations of feeds and temperatures using a factorial design. The diets were based on various Artemia enrichments: (a) Nannochloropsis sp, (b) Ori‐gold (Skretting) and (c) LC60 (Phosphotek). The temperatures chosen were in accordance with those found in their environment: 10°C (winter), 12°C (spring–autumn) and 14°C (summer), by triplicate. The factorial combinations were tested in two experiments with paralarvae of different age: Exp 1, from newly hatched to 14 days after hatching (DAH), and Exp 2, from that point to 42 DAH. It was concluded that temperature was the primary variable affecting mortality, feed intake, relative weight condition index, morphometric variables and trypsin activity. The enriched Artemia diets had the main impact on the leucine‐aminopeptidase activity, and on the fatty acid contents, mainly 20:5n‐3 (EPA) and 22:6n‐3 (DHA). Paralarval growth was increased by temperature with only one diet and at a certain age. Nutritional requirements varied between early and late paralarvae, and the possibility of changing the diets according to the development age is discussed.     

Hormonal sex reversal of tilapias: implications of hormone treatment application in closed water systems

The phenomenon of incidental sex reversal was observed in experiments originally designed to determine the importance of feeding duration and feed quality in the optimization of masculinization and feminization treatments of Oreochromis niloticus (L.) fry by oral application of hormones. Four separate experiments were conducted: (1) masculinization and (2) feminization using three feeding durations and (3) masculinization and (4) feminization using three alternative feed mixtures. Masculinization experiments incorporating 17 α-methyltestosterone (MT) into the feed at 40 mg kg^?1 were applied to putative monosex male progeny whilst feminization treatments were applied to putative all female fry using diethylstilboestrol (DES) at 1000 mg kg^?1. Treatments were applied outdoors in small cages suspended in 900-l circular concrete tanks with a flow through rate of 1-l min^?1. Replicate cages for all treatments and the controls in each experiment were reared together in the same tank. Only the first experiment produced significant differences in sex ratio, with the control treatment producing a slightly lower proportion of males than the three MT treatments at different durations. The most significant finding was that in all experiments the sex ratio of the control differed significantly from expectations and in all but experiment 1, did not differ from those of the treated fish in which sex reversal had clearly been effected. It appears likely that incidental sex reversal occurred in the control fish as a result of the accumulation of active metabolites from the treated fish and/or leachates from uneaten food given to fish in the same water body. The results are discussed in the context of improving the efficiency and safety of hormonal sex reversal treatments.     

The combined effects of temperature and salinity on embryos and larvae of the black-lip pearl oyster, Pinctada margaritifera (L.)

This paper reports on a 4 × 4 factorial design experiment conducted to examine the combined effects of temperature and salinity on embryonic development and growth and survival of black-lip pearl oyster, Pinctada margaritifera (L.) larvae. The temperatures used were 20 °C, 25 °C, 30 °C and 35 °C, and the salinities were 25°/_oo, 30°/_oo, 35°/_oo and 40°/_oo. Response surface contour diagrams were generated from the survival and growth data to estimate optimal conditions. Normal development of embryos occurred only from 25 °C to 30 °C. The optimal conditions for maximum survival and growth were 26–29 °C and 28–32°/_oo. Temperatures of 35 °C or greater were lethal for larvae and, at all temperatures tested, larval growth and survival were lowest at a salinity of 40°/_oo.     

A Qualitative and Quantitative Approach to Determine the Optimum Combination of Feeding Stimulants for Striped Bass Morone saxatilis Using an Agar Gel Carrier

A series of experiments was conducted to determine the optimum combination of previously identified feeding stimulants (FS), namely L-alanine (Ala), L-serine (Ser), inosine-5'-monophosphate (IMP), and betaine (Bet), for striped bass Morone saxatilis . Three experiments were conducted to determine the optimum combination of FS using an agar gel matrix as a carrier. In the first experiment a 2⁴ factorial experiment was conducted to test all possible combinations of the four FS at two levels, 0 and 0.1 M. Significant interactions between the FS were found, suggesting the complexity of gustatory stimulation and palatability. In the second experiment a 4 × 6 factorial design was employed to test each FS alone and at concentrations ranging from 0 to 8% in order to determine the minimum level at which maximal stimulation is achieved. The results suggest that there is no significant improvement in feed intake beyond the 1 % level of supplementation for all the FS. In addition, Ala produced a significantly greater response compared to all other FS. In the last experiment, a modified single factor method was used to estimate the optimum levels for each FS in a mixture. The range of the concentrations tested was 0–1% of the agar gel for each FS. Combining all four compounds yielded maximal stimulation. The levels of each compound in the final optimum combination of FS were: Ala, 0.4; Ser, 0.6; Bet, 0.4; and IMP, 0.3% of the agar gel.     

Clove oil as an anaesthetic for common octopus (Octopus minor, Sasaki)

We evaluated the anaesthetic effect of clove oil [2‐methoxy‐4‐2‐(2‐propenyl)‐phenol] on the common octopus (Octopus minor), in terms of the time required to become anaesthetized (‘anaesthetic time’) and recovery time. We used a factorial experimental design and administered clove oil at different temperatures (15, 20 and 25°C) and concentrations (50, 100, 150, 200, 250 and 300 mg L⁻¹). We observed a significant (P<0.05) relationship between concentration and temperature, and each variable was effective (P<0.05). Anaesthetic time linearly decreased as the concentration and temperature increased. However, recovery time increased as the concentration increased and temperature decreased. There was no mortality. A concentration of 200 mg L⁻¹ clove oil showed rapid anaesthetic and recovery times in the common octopus, indicating its suitability for this species.     

The effects of rearing water depths and feed types on the growth performance of African catfish (Clarias gariepinus)

African catfish (Clarias gariepinus) has been growing in popularity as a culture species globally. Although considerable research has been carried out on this species’ feeding preferences, no research has been carried out on optimum water level for growth. This is particularly surprising given this species' benthic nature. This study assessed the effect of different combinations of water levels and types of feed on the growth performance of African catfish. The study employed a 3 × 2 factorial design with three ponds of different water levels (0.5, 1 and 1.5 m) and two types of feeds (floating and sinking). Twelve earthen ponds (1 × 2 m) were each stocked with 16 catfish fingerlings (mean weight ~100 g), and their growth was monitored for 12 weeks. The fish cultured in the shallowest water grew significantly faster than those cultured in the deepest ponds. At the same time, fish cultured in the shallowest ponds had the lowest feed intake rates and consequently the lowest feed conversion ratios. Catfish fed sinking pellets grew faster than those fed floating pellets although the difference was not significant. There was no significant interaction between pond water depth and feed type. The results of this study suggest that the growth and feeding efficiency of C. gariepinus can be optimized by culturing in fairly shallow ponds (0.5 m).     

Comparison of experimental designs for estimating quantitative genetic parameters in fish

Four popular experimental designs for estimating variance components of additive genetic effects and (secondarily) dominance and maternal effects in fish (full‐sib families, half‐sib families, nested design and factorial design) were compared. The error variances of the estimators were formulated as functions of the true (hypothetical) values of genetic and environmental variances, depending on the experimental design considered, and whether the families were reared separately or mixed. Half‐sib families and rectangular (many sires×few dams) factorial design were most useful for the estimation of heritability. The nested design appeared much less adequate. The minimum experimental capacity for obtaining accurate estimates was 100 lots in separate rearing or 1000 fish in mixed rearing. A larger experimental capacity is required when dominance and maternal effects as well as heritability are to be estimated because these different estimations, requiring contradictory conditions, cannot be simultaneously optimized.     

The effect of food concentration on the scope for growth and growth performance of Ruditapes decussatus (L.) seed reared in an open-flow system

Ruditapes decussatus (L.) seed, 1.6 mm in length, was reared in an open-flow system for 28 days at different concentrations of food: 15, 50, 100, 200 and 300 Isochrysis galbana, clone T-ISO, cells μL^?1. Rates of ingestion, absorption, and respiration were measured during the experiment and used to calculate the energy balance. Rate of ingestion and absorption efficiency were the primary physiological processes governing seed growth. Ingestion rates increased with food concentration, up to a maximum of 100 cells μL^?1. Greater increases in concentration resulted in a decrease in ingestion. Clearance rates were inversely correlated to food concentration. Absorption efficiency, estimated using the Conover method, also decreased with increasing concentrations of food. Respiration rates were independent of food concentration. Potential growth rates were lower than actual growth rates for each of the concentrations tested, although the effect of food concentration on actual and potential growth was equal, with maximum growth occurring at a concentration of 50 cells μL^?1. Thus, SFG (‘scope for growth’) is a good qualitative estimator of actual growth, but a poor quantitative estimator.     

Synergistic effects of dietary vitamin E and selenomethionine on growth performance and tissue methylmercury accumulation on mercury‐induced toxicity in juvenile olive flounder,Paralichthys olivaceus (Temminck et Schlegel)

An 8‐week feeding trial was conducted to evaluate the synergistic effects of dietary vitamin E and selenomethionine (SeMet) on induced methylmercury (MeHg) toxicity in juvenile olive flounder Paralichthys olivaceus. Nine semi‐purified diets were formulated to contain three different vitamin E levels as DL‐α‐tocopheryl acetate (0, 100 and 200 mg TAkg^?1 diet) and three different selenium (Se) levels (0, 2 and 4 SeMet mg kg^?1 diet) on the constant mercury toxicity level (20 mg MeHgkg^?1 diet). Nine experimental diets, in a 3² factorial design (E₀Se₀, E₀Se₂, E₀Se₄, E₁₀₀Se₀, E₁₀₀Se₂, E₁₀₀Se₄, E₂₀₀Se₀, E₂₀₀Se₂ and E₂₀₀Se₄), were fed to triplicate groups of fish averaging 2.3 ± 0.04 g (mean ± SD) in the semi‐recirculation system. After 8 weeks of feeding trial, vitamin E and Se showed significant effects on weight gain (WG) of fish (P < 0.05). We found that there was a clear trend of increasing WG with elevating vitamin E and Se levels in the diets. Feed efficiency (FE), specific growth rate (SGR), protein efficiency ratio (PER) and survivability exhibited a similar trend with WG. Both antioxidants had significant interaction effects on FE and PER (P < 0.05). Methylmercury concentrations in fish muscle, liver and kidney decreases in a dose‐dependent manner as dietary vitamin E and Se levels increase. Interestingly, the most significant interactive effects of vitamin E and Se were found in liver tissue for depleting Hg concentrations (P < 0.05). These findings suggest that dietary vitamin E more than 100 mg TA kg^?1 diet with 2 or 4 mg SeMet kg^?1‐supplemented diets could have synergistic effects on growth and liver mercury bioaccumulation on MeHg‐induced toxicity in juvenile olive flounder.