Nutritional requirements of cobia, Rachycentron canadum (Linnaeus): a review

Cobia culture has been rapidly gaining in popularity since the early 1990s; however, the relative success of modified commercial diets in aquaculture has delayed the need for specific research into the nutritional requirements of cobia. Recent work has determined optimum dietary protein and lipid levels in juvenile cobia at 45 and 5–15% dry weight respectively. Maximum growth and feed conversion ratios have been recorded at 27–29 °C in juvenile cobia with an optimum ration level determined at 9% initial body weight per day. There is limited information on amino acid and essential fatty acids (EFA) requirements in cobia. Several studies have explored alternate protein sources in juvenile cobia with relative success observed with meat meal, yeast-based protein and various plant based sources including soybean meal. There is no literature on the vitamin or mineral requirements of cobia or the nutritional requirements of larger fish. Therefore future research should focus on the amino acid, EFA, vitamin and mineral requirements of cobia while the protein, lipid and energy requirements of larger cobia should be addressed. Additional work on feed ingredients, choice and palatability would also aid in maximizing culture production while minimizing costs thereby producing a more sustainable product.     

Dietary ascorbic acid requirement of cobia,Rachycentron canadum Linneaus

A 10‐week feeding trial was conducted to determine the optimal requirement of cobia (Rachycentron canadum Linneaus) for dietary ascorbic acid (AA). Graded levels of L‐ascorbyl‐2‐polyphosphate (LAPP) were supplemented in basal diet to formulate six semi‐purified diets containing 2.70 (the control diet), 8.47, 28.3, 80.6, 241 and 733 mg AA equivalent kg^?1 diet, respectively. Each diet was randomly fed to triplicate groups of fish in flow‐through plastic tanks (300 L), and each tank was stocked with 25 fish with average initial weight of 4.59 ± 0.36 g. Observed deficiency signs included poor growth, higher mortality and lower feeding rate (FR) in the fish of the control group. Fish fed the control diet had significantly lower weight gain (WG), lower feed efficiency ratio (FER) and lower tissue AA concentrations in fish liver and muscle. With the increase of dietary AA, the survival, WG, FER, hepatic and muscular AA concentrations of cobia significantly increased and then levelled off. The dietary AA requirement of cobia was estimated to be 44.7 mg kg^?1 based on WG, 53.9 mg kg^?1 or 104 mg kg^?1 based on either hepatic or muscular AA concentration, respectively.     

Free amino acid distribution in plasma and liver of juvenile cobia (Rachycentron canadum) fed increased levels of lizardfish silage

Juvenile cobia (Rachycentron canadum) (100 g) were fed four moist diets (447–476 g kg^?1 dry wt) where 0, 130, 260 or 390 g kg^?1 of concentrated lizardfish (Saurida undosquamis) silage replaced fresh lizardfish, respectively. Blood and livers were sampled at 0, 6, 12, 24 and 48 h postfeeding at the end of the 3‐week experiment. At 6 h postfeeding in all groups, maximum concentrations of most plasma essential amino acids were observed, while significantly lower levels of most non‐essential amino acid levels were recorded compared to the other sampled times. At 6 and 12 h after feeding, the concentration of most plasma free amino acid (FAA) increased with an increase in dietary fish silage levels. Most FAA in livers of all groups peaked at 12 and 24 h postfeeding. However, at 48 h postfeeding, concentrations of most plasma FAA were significantly higher in fish fed 0% silage‐based diet than in fish fed the other diets (4999 versus 3390–4339 nmol AA mL^?1 plasma). Growth rates and feed utilization were significantly lower in cobia fed 26% or 39% silage‐based diets than in fish fed 0% or 13% silage‐based diets. Different levels of silage protein thus seemed to have effects on growth and feed utilization efficiency of juvenile cobia. Results from this study support the premise that fish silage can be included until 130 g kg^?1 in cobia diets.     

Evaluation of iron methionine and iron sulphate as dietary iron sources for juvenile cobia (Rachycentron canadum)

An 8‐week experiment was designed to determine the optimum dietary iron requirement of juvenile cobia Rachycentron canadum (mean initial weight, 15.89 ± 0.84 g) with iron sulphate (FeSO₄•7H₂O) and iron methionine (FeMet) as iron sources, using a semi‐purified diet based on casein and white fish meal as the protein sources. The basal diet was supplemented with 0, 30, 60, 120, 240 and 480 mg iron kg⁻¹ dry diet from either FeSO₄ or FeMet, respectively. Survival was not significantly affected by the all dietary treatment. Weight gain (WG), feed efficiency (FE), serum catalase activity (SCAT), and haemoglobin were significantly affected by any of the dietary treatments from both of two iron sources. Based on broken‐line regression analysis of WG, FE and SCAT, a minimum requirement for dietary iron was recommended to be 80.5–94.7 mg kg⁻¹ from FeSO₄ and 71.3–75.1 mg kg⁻¹ from FeMet. Iron supplement to the basal diet had no significant effect on haematocrit, erythrocyte count, iron concentration in whole body and fillet. Our experiment also showed that the bioavailability of FeMet and FeSO₄ to juvenile cobia was similar for WG and FE, and the relative bioavailability of FeMet and FeSO₄ to juvenile cobia was 275% for maximum SCAT.     

Whole-body amino acid pattern of juvenile,preadult, and adult pacu,Piaractus mesopotamicus,with an estimation of its dietary essential amino acid requirements

In the present study, juvenile (live body weight, 54.3 ± 8.2 g), preadult (live body weight, 822.5 ± 33.9 g), and adult (live body weight, 1,562.8 ± 41.8 g) pacu, Piaractus mesopotamicus, were used to estimate their dietary essential amino acid (EAA) requirements using the whole-body amino acid (AA) pattern. The results showed that whole-body moisture, crude protein, total lipid, and ash contents expressed on a wet weight basis (%) were significantly different among the studied growth phases. No significant differences were observed in the dietary EAA requirements estimated for the three growth phases of pacu. These dietary EAA requirements were found to be different than those previously estimated for the same fish through its muscle AA pattern. Based on whole-body EAA to total EAA ratios {A/E ratios; [(each EAA/total EAA) × 1,000]}, EAA requirements were estimated to be histidine (0.42%), arginine (1.36%), threonine (0.82%), valine (0.90%), methionine (0.45%), isoleucine (0.83%), leucine (1.29%), phenylalanine (0.74%), lysine (1.64%), and tryptophan (0.14%) for pacu. These estimated requirements may serve as a reference line in the formulation of practical and experimental diets until dose–response-based optimum EAA requirements are available for pacu.     

Effect of dietary carbohydrate level on growth performance,body composition,apparent digestibility coefficient and digestive enzyme activities of juvenile cobia,Rachycentron canadum L

A 9‐week feeding trial was conducted to investigate the effect of dietary carbohydrate level on the growth performance, body composition and apparent digestibility coefficient and digestive enzyme activities of juvenile cobia. Six isonitrogenous and isolipidic diets containing graded levels of starch (1.3%, 6.5%, 12.5%, 18.4%, 24.2% and 30.4%) were fed to juvenile cobia. Specific growth rate (SGR), feed efficiency ratio (FER) and protein efficiency ratio (PER) increased with increasing dietary starch up to 18.4% (P<0.05), and thereafter SGR declined but FER and PER remained nearly the same. Apparent digestibility coefficient of starch reduced significantly when dietary starch up to 30.4%. Fish fed the diets with starch from 18.4% to 30.4% showed higher amylase activities in intestinal tract than those fed diets containing starch 1.3% and 6.5% (P<0.05). Significantly higher whole‐body lipid contents were observed in fish fed the diets containing higher starch. Whole‐body moisture content was inversely correlated with whole‐body lipid content, while protein and ash showed no significant differences. Plasma glucose, hepatosomatic index, liver glycogen and liver lipid increased with an increasing dietary starch. Based on SGR and FER, the appropriate dietary starch supplementations of juvenile cobia were estimated to be 21.1% and 18.0 % of diet respectively.     

No significant effect of additive ratios of docosahexaenoic acid to eicosapentaenoic acid on the survival and growth of cobia (Rachycentron canadum) juvenile

An experiment was conducted in the laboratory to investigate the effects of additive ratios of docosahexaenoic acid (DHA) to eicosapentaenoic acid (EPA) on the growth and survival of cobia (Rachycentron canadum) juveniles from August to October 2005. Three hundred and eighty cobia juveniles (56 days of age, body weight 6.9 ± 0.1 g, body length 9.2 ± 0.1 cm) were selected and 20 of them were freely taken for initial sample analysis in the week 0. Additional 360 juveniles were randomly assigned into eight groups with triplicate, total 24 tanks with 15 fish each. Cobia juveniles were reared in glass‐steel tanks (200‐L volume per tank) using filtered seawater with temperature 26–30.5 °C, salinity 25.4–33.0 g L^?1 and pH 7.8–8.0. Cobia juveniles were fed for 8 weeks using seven treatment diets (D‐1 to D‐7) with the same amount of DHA and EPA (15.0 ± 1.2 g kg^?1 of dried diet), but varying ratios of DHA to EPA (0.9, 1.1, 1.3, 1.5, 1.7, 1.9, 2.1, respectively) and a control diet (D‐0, DHA + EPA = 8.0 g kg^?1 of dried diet, DHA/EPA = 1.3). Five juveniles per tank were randomly taken for sample analysis at the end of weeks 4 and 8, respectively. The highest protein efficiency rate (PER; 1.5 in mean), average body weight (BW; 73.3 g per fish in mean) and the lowest feed conversion ratio (FCR; 1.6 in mean) were obtained in cobia juveniles fed the control diet at the end of week 8. These parameters were significantly different (P < 0.05) among juveniles fed the control and treatment diets; however, no significant difference (P > 0.05) was found among juveniles fed the treatment diets evaluated in this study. It was concluded that the survival and growth of cobia juveniles were not greatly influenced by additive ratios of DHA to EPA in our experimental conditions.     

Effects on digestibility and growth of juvenile cobia (Rachycentron canadum) fed fish or crab silage protein

The study was conducted in Cam Ranh, Vietnam, in 1000‐L tanks supplied with recirculated and biofiltered saltwater (33‰ and 28.4 °C) to evaluate the potential use of lizard fish (Saurida undosquamis) or blue crab (Portunus pelagicus) acid silage protein for juvenile cobia (23–25 g). Six isoenergetic test moist diets (4915–5125 kcal kg^?1), using either raw fish diet, fish silage diet (FSD), raw crab diet, crab silage diet (CSD), mixed raw fish/raw crab diet or mixed fish/crab silage diet (MSD), as part of the protein sources in the steam‐cooked diets, were fed to satiety to triplicate groups of 20 fish each for a 6‐week growth trial. Y₂O₃ was added as an inert indicator to determine the apparent digestibility coefficients (ADC) for macro nutrients and gross energy. Weight gain (185–286%) and specific daily growth rate (2.5–3.2% per day) were significantly higher in cobia fed the raw‐based diets and FSD than in fish fed CSD and MSD (34–90 and 0.7–1.5% per day). Feed conversion ratios (FCR) were significantly higher in the groups fed CSD and MSD diets (2.1–6.5) than the groups fed the other diets (1.0–1.2), resulting in significantly lower protein productive values (0.1–0.2) in the groups fed CSD and MSD than in the other groups (0.3–0.4). The FCR results were confirmed by significantly lower ADC values in fish fed CSD and MSD than those in fish fed the other diets. We thus conclude that the present raw‐based diets were better utilized by juvenile cobia than silage‐based diets, particularly the diet made from crab silage.     

Effects of dietary starches and the protein to energy ratio on growth and feed efficiency of juvenile cobia,Rachycentron canadum

Optimization of the protein to energy ratio in juvenile cobia (Rachycentron canadum) would allow the production of diets that maximize growth without the addition of excess energy that may increase costs or even be detrimental to the health of the fish. During a 6‐week growth trial, juvenile cobia (5.6 ± 0.5 g fish^?1 initial weight) were fed five isonitrogenous and isolipidic diets containing various protein to energy ratios using starch as the energy source. At the end of the trial, some fish were analysed for body composition characteristics while the rest were used to examine the excretion of dietary starch in the feces. Survival and growth were not significantly affected, but feed efficiency (ranging from 0.64 to 0.94) and daily consumption (ranging from 45.3 to 64.1 g kg^?1 of body weight d^?1) were affected. No reduction in consumption due to excess energy was noted. Analysis of the fecal carbohydrate data showed a linear relationship between dietary inclusion and excretion of carbohydrates with no sign of reaching saturation. Results of this study suggest that cobia can utilize dietary carbohydrates up to at least 340 g kg^?1 of dry diet with an optimal protein to energy ratio of approximately 34 mg protein kJ^?1metabolizable energy.     

The role of dietary methionine concentrations on growth,metabolism and N‐retention in cobia (Rachycentron canadum) at elevated water temperatures

This study determined impacts of dietary methionine concentrations at two temperatures on growth, feeding efficiency and N‐metabolites in juvenile cobia. Methionine concentrations of the experimental diets were deficient (M9; 9 g/kg), sufficient (M12; 12 g/kg) and surplus (M16, 16 g/kg). Water temperature was normal (30°C) or elevated (34°C). Twenty cobia in triplicate tanks were fed the experimental diets for 6 weeks. Both methionine and temperature affected cobia's growth and feeding efficiency. Cobia fed M9 performed lower than the fish fed M12 and M16 diets. Additionally, cobia reared at 34°C performed poorer than at 30°C, probably due to lower voluntary feed intake in the fish reared at 34°C. Protein efficiency ratio and protein productive value in cobia fed M9 diet were less than M12 or M16 diets. This was confirmed with the improved retentions of indispensable amino acids (AAs). No interactions between methionine and temperature were observed in growth and protein accretion. At 30°C, CF improved, while HSI and VSI declined upon methionine supplementation levels. Of which an interaction between temperature and methionine was present. Plasma, muscle and liver free AA and N‐metabolites were affected by methionine and temperature. Furthermore, temperature affected cobia's lipid class composition, resulting in increased phospholipids and cholesterol at 34°C.     

Growth,feed efficiency and body composition of juvenile cobia (Rachycentron canadum Linnaeus, 1766) fed increasing dietary levels of shrimp protein hydrolysate

A shrimp protein hydrolysate (SPH) containing 894.2 g kg⁻¹ crude protein (CP) and 54.3 g kg⁻¹ total lipids was tested as a partial replacement for fish meal (FM) in diets of juvenile cobia. The effects of increasing dietary levels of SPH on the survival, weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR), nitrogen retention efficiency (NRE) and daily feed intake (DFI) of cobia with initial body weight of 11.9 g were evaluated. Four isoproteic (from 431.1 to 439.7 g kg⁻¹) and isoenergetic (20 825–21 347 MJ kg⁻¹) diets were formulated to contain 0 (Control), 120, 240 or 360 g kg⁻¹ of dietary CP derived from SPH. Survival, WG, SGR, FCR, NRE and DFI ranged from 90 to 100%, 40.2–56.5 g, 4.7–6.1% day⁻¹, 1.04–1.54, 26.3–44.0% and 4.7–6.0% fish⁻¹ day⁻¹ respectively. Survival and DFI were not affected by the dietary treatments. On the other hand, fish fed the control diet and the one containing 120 g kg⁻¹ SPH had higher WG, SGR and FCR. Nitrogen retention efficiency was significantly higher for fish fed diets 0 and 120. It is concluded that up to 120 g kg⁻¹ of SPH in cobia diets can be used with no significant effects on feed utilization and fish performance.     

The effect of different levels of dietary phospholipid on growth, survival and nutrient composition of early juvenile cobia (Rachycentron canadum)

This experiment was conducted to evaluate the effect of different levels of dietary phospholipid (PL) on growth, survival and nutrient composition of 25 days posthatch cobia Rachycentron canadum (0.4 g initial wet weight). For 42 days, fish were fed fish meal and protein hydrolysate based diets containing four PL levels (0, 20, 40 and 80 g kg^?1dry matter: purity 97%) and phosphatidylcholine purity was 60%. All diets were isonitrogenous and isolipidic by regulating the fish oil and maize oil levels. Weight gain (2601–10892%), specific growth ratio (7.82–11.18) and survival (49–100) were significantly affected by dietary PL. Intraperitoneal fat ratio (0.19–0.74) and hepatosomatic index (2.67–3.08) increased with dietary PL level. The effect of dietary PL levels on the chemical composition of tissues was significant only for whole body and liver. The contents of plasma total cholesterol (2.47–3.77 mmol L^?1) and PL (1.03–2.97 mmol L^?1) increased with an increase in dietary PL. In conclusion, in our study survival and growth continued to increase even at the highest PL levels used (80 g kg^?1); therefore optimal dietary PL levels may well exceed 80 g kg^?1 for early juvenile cobia requirement. It also indicated from the experiment that PL could affect lipid deposition and resulted in a higher lipid level in fish tissue.     

Effect of replacing dietary fish oil with soybean oil on production performance and fillet lipid and fatty acid composition of juvenile cobia Rachycentron canadum

As a marine carnivore exhibiting exceptionally high growth rates, cobia are considered a species for which fish oil (FO) replacement may be difficult. However, partial, if not complete, FO replacement is necessary to ensure sustainability. We evaluated the effects of graded substitution of dietary FO with soybean oil (SO) in cobia culture. Feeds contained FO (100% FO), SO (0% FO) or blends of the two (67% FO, 33% FO) as the supplemental lipid source. Production performance was largely unaffected by partial replacement of FO with SO: feed intake and final weight were reduced only in the 0% FO dietary treatment. Fillet total lipid fatty acid (FA) composition differed among the dietary treatments, closely approximating dietary FA profile. As increasing amounts of FO were replaced, SO‐associated FA became enriched within the fillet lipid at the expense of FO‐associated FA. Fillet lipid classes were associated with a particular FA signature, regardless of dietary FA profile. SO can replace a substantial amount of dietary FO; however, juvenile cobia appear to exhibit a nominal requirement for intact long‐chain polyunsaturated FA. Therefore, aggressive FO replacement may result in essential fatty acid deficiencies unless the feeds can be amended with alternative sources of these essential nutrients.     

Dietary vitamin E could improve growth performance,lipid peroxidation and non‐specific immune responses for juvenile cobia (Rachycentron canadum)

An 8‐week feeding trial was conducted to establish the dietary vitamin E requirement of juvenile cobia. The basal diet was supplemented with 10, 20, 30, 40, 60, 120 mg vitamin E kg^?1 as all‐rac‐α‐tocopheryl acetate. The results indicated that fish fed the diets supplemented vitamin E had significantly higher specific growth rate, protein efficiency ratio, feed efficiency and survival rate than those fed the basal diet. It was further observed that vitamin E concentrations in liver increased significantly when the dietary vitamin E level increased from 13.2 to 124 mg kg^?1. Fish fed the basal diet had significantly higher thiobarbituric acid‐reactive substances concentrations in liver than those fed the diets supplemented vitamin E. Fish fed the diets supplemented with 45.7 and 61.2 mg kg^?1 vitamin E had significantly higher red blood cell and haemoglobin than those fed the basal diet, while fish fed the diets supplemented with 61.2 and 124 mg kg^?1 vitamin E had higher immunoglobulin concentration than those fish fed the basal diet. Lysozyme and superoxide dismutase were significantly influenced by the dietary vitamin E level. The dietary vitamin E requirement of juvenile cobia was established based on second‐order polynomial regression of weight gain and lysozyme to be 78 or 111 mg all‐rac‐α‐tocopheryl acetate kg^?1 diet, respectively.     

Effects of salinity on growth characteristics and osmoregulation of juvenile cobia,Rachycentron canadum (Linnaeus 1766), reared in potassium‐amended inland saline groundwater

The suitability of inland saline groundwater as a medium to culture juvenile cobia, Rachycentron canadum, was assessed. In the first experiment, juvenile cobia stocked in raw (unamended) saline groundwater at salinities of 5, 10, and 15 g/L exhibited complete mortality after 108, 176, and 195 hr, respectively. The second experiment evaluated the rearing of juvenile cobia (mean weight ~9.23 ± 0.12 g) in potassium (K⁺)‐amended saline groundwater (100% K⁺ fortified) and reconstituted seawater at salinities of 5, 10, and 15 g/L to assess growth and osmoregulation in distinct culture media. Following 60 days of culture, all fish survived the experimental period. Final mean bodyweight of cobia reared in K⁺‐amended saline groundwater (103.2–115.8 g) and seawater (111.2–113.8 g) of different salinities did not vary significantly (p > .05). No differences (p > .05) were observed in specific growth rate, weight gain (%), and feed conversion ratio between treatment groups. Serum osmolality increased with salinity and was significantly higher (p < .05) for fish in K⁺‐amended saline groundwater (353–361 mOsmol/Kg) than in reconstituted seawater (319–332 mOsmol/Kg), although differences were not observed between salinities by water type. Cobia stocked in saline groundwater of different salinities were osmoregulating normally, and the higher values observed may be because of variations in ionic composition and other interfering ions in saline groundwater. Trial results suggest that juvenile cobia can achieve optimal growth in K⁺‐amended saline groundwater of low and intermediate salinities.     

Assessment of the ideal ratios of digestible essential amino acids for pacu,Piaractus mesopotamicus,juveniles by the amino acid deletion method

The present study aimed to determine the ideal ratios of digestible essential amino acids (EAAs) for pacu (Piaractus mesopotamicus) juveniles by the amino acid (AA) deletion method. A completely randomized design which consisted of 11 treatments and three replicates each was used. The treatments included a control diet (CD) containing 55% of nonpurified natural ingredients and 45% of purified synthetic amino acids and ingredients, and other ten isonitrogenous and isoenergetic EAA limiting diets (LDs), each being deficient in 44.4 ± 0.02% of the respective EAA. Pacu juveniles with initial average body weight of 6.22 ± 0.09 g were distributed among 33 fiber glass tanks. Fish were fed with semipurified and extruded diets for 113 days two times a day until apparent satiation. The ideal ratio of each dietary EAA was calculated on the basis of the relationship between body N retention and amount of EAA deleted from the respective EAA LD. Based on the AA deletion method, the ideal ratios of digestible EAAs for pacu juveniles, relative to lysine requirement of 100% were estimated as: methionine 14.6%, threonine 35.0%, tryptophan 6.6%, arginine 62.8%, histidine 13.6%, isoleucine 26.3%, leucine 43.7%, phenylalanine 27.2%, and valine 35.8%.     

Arginine and phenylalanine requirement of juvenile silver perch Bidyanus bidyanus and validation of the use of body amino acid composition for estimating individual amino acid requirements

An experiment was conducted in a closed system to quantify the arginine requirement of juvenile silver perch Bidyanus bidyanus . Five experimental diets were formulated to contain 40% crude protein with five graded levels of arginine. The diets contained casein and gelatine as protein sources supplemented with crystalline L -amino acids to simulate the reference amino acid profile (except for arginine) of silver perch tissue protein. The experiment lasted 12 weeks and, based on growth data using broken-line analysis, the arginine requirement of juvenile silver perch was found to be 2.7 g 100 g⁻¹ dry diet (or 6.8% of protein).
Based on whole-body amino acid composition, A/E ratios (essential amino acid/total essential amino acids + (cystine + tyrosine) × 1000) were estimated. Using the experimentally determined requirement for arginine and A/E ratios, the phenylalanine requirement of silver perch was predicted to be 5.5 g 100 g⁻¹ protein. Another feeding trial was conducted to determine the phenylalanine require-ment of silver perch using a series of diets with various amounts of phenylalanine and a protocol similar to the previous one. It was found that the experimentally determined phenylalanine requirement of juvenile perch was similar to that predicted. The A/E ratios have been hitherto utilized for the estimation of essential amino acid requirements in three salmonids, common carp and channel catfish: the present findings extend the validity of the method to other fish species.     

Evaluation of fermented soybean meal in the practical diets for juvenile Chinese sucker,Myxocyprinus asiaticus

The study was designed to investigate the influence of fermented soybean meal (FSBM) on the growth and feed utilization of juvenile Chinese sucker, Myxocyprinus asiaticus. Seven isonitrogenous and isolipidic diets were formulated with 0%, 15%, 25%, 35%, 45%, 55% or 65% replacement of fish meal with FSBM on a protein basis. Each diet was fed to three replicate groups of fish with an initial weight 4.59 ± 0.2 g for 8 weeks. Weight gain (WG) and specific growth rate (SGR) was significantly lower when FSBM inclusion was 391 g kg^?1 or greater, replacing more than 45% fish meal protein. A significant negative relationship was observed between growth response and the level of fish meal protein replacement with FSBM. Methionine and Lysine content decreased as FSBM inclusion levels increased, consequently compromising growth performance. Feed intake (FI) were unaffected by dietary FSBM levels. The feed conversion ratio (FCR) of fish fed D‐0, D‐15, D‐25 and D‐35 diets was significantly lower than those fed other diets. The protein efficiency ratio (PER) was highest at the lowest FSBM inclusion level. Experimental diets D‐0, D‐15, D‐25 and D‐35 had apparent dry matter digestibility ranging from 71.2% to 72.6% and apparent protein digestibility (ADPs) from 89.1% to 90.1%, while the diets with higher FSBM inclusion (D‐45 to D‐65) had a significantly lower apparent dry matter digestibility range (69.7–70.3%) and ADPs range (88.5–88.9%). It is concluded that FSBM is an acceptable alternative plant protein source that can replace up to 35% of fish meal protein in diets without significant adverse effects on growth, survival, FCR, PER and body composition.