CHANGES IN CRAWFISH PRODUCTION COSTS AND CURRENT PRODUCTION PRACTICES USED

Louisiana State University Agricultural Center cost estimates for single-crop crawfish production costs are analyzed for the period, 1991–2010, to determine changes in the cost components of Louisiana crawfish production. Fuel costs have contributed the most and fixed expenses the least to increased production costs, with total expenses per acre increasing by an average of 3.8% per year if land is not included and by 3.6% per year if land is included. Crawfish prices have varied greatly over the period, ranging from $0.50/lb in 1993 to $1.75/lb in 2000. Production practices used by Louisiana crawfish producers are highly variable, creating challenges for estimating representative production cost estimates.     

Consumer Acceptability and Composition of Crayfish Harvested from Commercial Production Fields and Moist-Soil Wetlands

ABSTRACT

The consumer acceptability and proximate and fatty acid composition of crayfish (Procambarus clarkii) harvested from commercial systems and moist-soil wetlands were evaluated. Aroma and appearance acceptability scores for abdominal muscles from commercial crayfish were higher over samples from moist-soil wetlands. Aroma and texture acceptability scores for whole crayfish from commercial fields were also higher compared to moist-soil wetland samples. No differences existed between treatments for flavor and overall acceptability. Results indicate that although scores for aroma were slightly higher for commercial crayfish, crayfish from both populations were acceptable to consumers. Hierarchical cluster analyses of panelists’ scores for overall acceptability revealed that 25% of panelists rated moist-soil wetland and commercial crayfish abdominal samples equally high, and an additional 31% of panelists rated moist-soil wetland crayfish samples as more liked than commercial crayfish samples. Few differences existed in crayfish proximate composition and fatty acid content from the two harvest practices.     

Economics of milkfish (Chanos chanos) production in Hawaii*

Abstract

Economic evaluations of commercial milkfish (Chanos chanos) growout systems were made based on current Hawaiian fishpond, pond and tank culture techniques in Hawaii. Based on the observed practices of milkfish culture as a secondary or tertiary crop, capital costs and several operating costs were pro‐rated to accurately depict current farm practices. For a target harvest weight of 0.80 lb, the study estimates the total production cost for milkfish production at $3.31/lb for the pond system, $3.81/lb for the tank system and $1.84/lb for the Hawaiian fishpond system. At a sale price of $3.00/lb and seed cost of $0.25/fingerling, only the Hawaiian fishpond system is profitable under a 20‐year project life. When considering variable costs alone, the production cost is $1.78/lb for the pond system, $2.33/lb for the tank system and $1.53 for the Hawaiian fishpond system, yielding returns on variable costs of 67%, 30% and 59% respectively. Analyses of profit sensitivity to sale price, production yield, labor, feed and stocking indicate that sale price, as expected, has the largest impact on profitability, followed by feed. The results of this study are consistent with the Hawaii farmers’ view of milkfish as a secondary specie to core production based upon current market conditions and input requirements.     

The biological response of the crayfish Procambarus clarkii to transplantation into California ricefields

The population dynamics of the crayfish Procambarus clarkii was studied in California ricefields to investigate the effects of range extension and to examine its potential for harvest. The species was shown to undergo distinct cycles of activity related to depth, temperature and reproduction. Juveniles were observed to have two peaks in activity during late summer and winter, while adults only had a single peak. Ovarian maturity was found during summer and maximum hatching occurred in late summer and winter. Males matured at 35.8 mm carapace length (CL) on the average, while females matured at 36.5 mm CL. A direct correlation between female egg production and body size was noted. P. clarkii in California were shown to be cued into similar cycles as Louisiana crayfish, even though the timing and extent of the hydrological cycle was considerably different. Breeding activity paralleled the Louisiana crayfish, while winter-spring juvenile growth rates (16.32 mm in 120 days) and biomass (208 kg/ha) were much lower. Crayfish emigration during ricefield draining was found to be substantial (31% of population) and may provide an excellent opportunity for harvest.     

Influence of water quality,local knowledge and river–floodplain connectivity on commercial wild crayfish harvesting in the Atchafalaya River Basin

Water quality and river connectivity influence fisheries, but their role is not understood in wild crayfish harvest, or how water quality and river connectivity are incorporated into crayfish harvest strategies. In Louisiana, wild harvesting practices were evaluated with field observations and interviews with individual harvesters. Field observations included trap locations, water quality, water stable isotopes (2016) and habitat components over two seasons (2015 and 2016). Traps were set in less turbid water (NTU < 69.4), in depths from 1 to 3 m or 3 to 3.6 m and in locations associated with river water inputs. Harvester interviews indicated the importance of tradition (35%‐47% respondents), depth (88% respondents) and water colour (>40% respondents; a surrogate for turbidity and connectivity) in harvesting initiation and trap locations. Harvesters appeared to follow lateral water movements onto and within the floodplain, likely based on local environmental knowledge.     

The harvest of the freshwater crayfish <Emphasis Type="Italic">Astacus leptodactylus</Emphasis> Eschscholtz in Turkey: harvest history,impact of crayfish plague,and present distribution of harvested populations

This review focuses on the present distribution of populations of the crayfish Astacus leptodactylus that are harvested in Turkey. It also examines the history of this harvest and the impact that crayfish plague has had on them. Crayfish plague, caused by the fungus-like organism, Aphanomyces astaci Schikora, 1906, is a severe parasite of freshwater crayfish and has caused a lot of damage to A. leptodactylus populations in Turkey since 1984. Turkey was the largest provider of A. leptodactylus to Western Europe from 1970 (or possibly earlier) until 1986. For example, the peak production was reached in the early 1980s, with over 5,000 tonnes being exported in 1984. On the other hand, as a result of the crayfish plague the harvest of A. leptodactylus was reduced severely in most populations in Turkey after 1985. The harvest was only 320 tonnes in 1991. After the occurrence of crayfish plague in Turkey, in order to increase crayfish production uncontrolled A. leptodactylus stockings have been carried out in many waterbodies throughout Turkey. These introductions have caused an increase in the number of A. leptodactylus populations, but exploitation of A. leptodactylus is still under the pressure of the plague, although there has been a steady increase in crayfish production in recent years. The harvest increased to 2,317 tonnes in 2004. Fortunately, among those populations affected by crayfish plague, large amounts of A. leptodactylus can still be harvested from three lakes, ?znik (Bursa), E?irdir (Isparta) and Çivril (Denizli). Thus, it seems that A. leptodactylus has a degree of resistance to crayfish plague. It is therefore interesting to investigate the resistance of A. leptodactylus caught from these populations to crayfish plague.     

Economic Evaluation of a Small-Scale Recirculating System for Ongrowing of Captive Wild Black Sea Bass Centropristis striata in North Carolina

An economic analysis of a hypothetical small‐scale marine recirculating aquaculture system (RAS) is conducted for ongrowing small, wild black sea bass Centropristis striata at the University of North Carolina Wilmington, Center for Marine Science (UNCW‐CMS) aquaculture facility in Wrightsville Beach, North Carolina (NC). The analysis is based on production data from field trials and marketing data from the sale of tank‐grown product. The growout facility consists of four 16.7‐m³ (dia. x ht. = 5.58 × 1 m) fiberglass tanks supported by state‐of‐the‐art RAS components, including particle traps and swirl separators, drum screen filter, trickling biological filter, UV sterilizer, heat pump, protein skimmer, and oxygen cone. Wild‐caught, above minimum legal size black sea bass (24.2 cm TL, 350 g, 0.77 lb) were purchased from a commercial fisherman for $3.14/ kg ($1.4011b), stocked at a density of 21.1 kg/m³, and grown to a final weight of 1 kg (2.24 lb) in 200 d at 23 C resulting in 1.8 production cycles per year. Fish were fed a commercial pelleted diet ($0.94/kg; $0.42/Ib) with a feed conversion ratio of 1.5. Final harvest density was 60 kg/m³ (0.50 lb/gal), and total harvestable weight was 3,982 kg (8,919 Ibs) of fish per cycle, or 6,760 kg (15,022 lb) per year. The economic analysis assumes that the facility owner manages and operates the system on coastal property zoned commercial/industrial, where full strength seawater is available on demand from natural sources. Under the base case scenario, initial investment in construction and equipment is $84,506 (10‐yr life), fish are grown to a harvestable weight of lkg/fish (2.24 lb/fish), product price (farm gate basis) is $10.10/kg ($4.50/lb), and breakeven price is $7.02/kg ($3.13/lb). Depreciation, fingerlings, interest paid, electricity, and feed, account for 19.6%,17.4%, 16.9%, 16.6%, and 12.3%, respectively, of total annual costs. Measures of financial performance for the base case, 10‐yr scenario are: annual return to management, $18,819; net present value (5% discount rate), $145,313; internal rate of return on initial investment, 37%; and discounted payback period on initial investment, 3.2 yr. Sensitivity analysis showed that product price changes have the largest impact on annual returns, while changes in daily growth rate, initial weight, and survival have a strong impact on financial performance. Moderate effects are seen with changes in fingerling costs, feed costs, feed conversion ratio (FCR), final weight, and interest rates.     

Effects of Harvest Period on the Production of White River Crayfish,Procambarus acutus acutus

Abstract

Crayfish harvest was initiated at a cool water temperature (15°C) and warm water temperature (20°C) from culture ponds (0.1 ha) with a resident population of white river crayfish, Procambarus acutus acutus.Crayfish were harvested for 24 days for a total of 1,977 trap-days/ha (March 9-May 12, 2000 from the cool-harvest treatment and May 5-June 15, 2000 from the warm-harvest treatment). The mean total length (TL) and production of harvested white river crayfish (WRC) was similar between treatments. The population structures of WRC from the cool and warm periods of harvest were substantially different; large WRC (≤100 mm TL) from the cool-harvest period were 3.1 times more abundant than large WRC during the warm-harvest period. A similar number of small WRC were harvested from the two treatments; however, those small WRC harvested during the warm period was significantly longer than the small WRC during the cool-harvest period. The estimated large WRC biomass contribution to the total harvest from the cool-harvest period was 37% in comparison to 15% during the warm-harvest period. The estimated dollar value of the production during the cool-harvest period was 40% more than that from the warm-harvest period.     

Effect of different harvesting techniques on the production and population structure of Macrobrachium rosenbergii in a wetland ecosystem of South India

Culling prior to final harvest has shown many advantages in improving the marketable yield in freshwater prawn farming. This study is an attempt to compare three harvesting techniques on the production and population structure of Macrobrachium rosenbergii farming in a wetland ecosystem of South India. The study also compares the marketable yield structure and economics of farming of these prawns in three quadruplicate sets of polders following either complete harvest (T1) or traditional partial harvest through dewatering and cast netting (T2) or a modified cull harvest (T3) with a newly designed drag seine. Results showed better yield and faster morphotype transformation among treatments that followed cull harvesting. Among them, better results on mean weight and survival rate (64 g and 54% respectively) were recorded from T3. The results also showed that irrespective of the type of cull harvesting, their inclusion in polders facilitated faster morphotypic transformation and thenceforth the preponderance of terminal morphotypes in the harvested population. Likewise, larger sized male morphotypes were significantly higher (35% and 25% respectively) in T2 and T3. The net production also varied significantly within the treatments from 140 kg ha^?1 in T1 to 515 kg ha^?1 in T3. From a marketability point of view also, the total marketable prawns (>50 g group) varied considerably from 94% (T2) and 92% (T3) to 78% in T1. While working out the harvest economics through benefit–cost analysis, it was inferred that the introduction of the new harvest technique was more profitable compared to the traditional systems prevailing in Kuttanad. This study also emphasizes the need for resorting to modified partial harvesting through the use of drag seines, as it considerably reduces the cost on harvesting in a waterlogged ecosystem such as Kuttanad.     

Comparative Economics of US Catfish Production Strategies: Evidence from a Cross‐sectional Survey

Understanding the effects of specific management strategies on yields and economic outcomes on commercial catfish farms could provide useful guidance to catfish farmers on the most profitable sets of production practices. Data from the U.S. Department of Agriculture–National Animal Health Monitoring System (USDA–NAHMS) 2009 survey of production practices on catfish farms in Alabama, Arkansas, Louisiana, and Mississippi were used to identify five clusters of catfish farms that use various stocking densities, channel versus hybrid catfish, different aeration levels, and utilize automated oxygen sensors. The lowest production costs ($1.96/kg) were found in cluster 1 and were followed in order of increasing costs per kilogram of clusters 2 and 4 ($2.16/kg) and cluster 5 ($2.73/kg); the highest cost corresponded to cluster 3 ($2.84/kg). The lowest risk levels corresponded to the clusters with the lowest production costs per kilogram of fish and the highest risk levels to the highest production costs. This analysis demonstrated that different types of management models can achieve similar levels of production costs ($/kg), and it appears that there is not one single economically optimum way to raise catfish. The key to least‐cost production is to balance the use of inputs, their associated costs, and the yield produced to achieve economic efficiency within the farm's overall business and management model.     

Preliminary Pond Production of the Red Claw Crayfish,Cherax Quadricarinatus,in the Central United States

The Australian red claw crayfish, Cherax quadricarinatus, has recently attracted attention as a potential candidate for aquaculture in the United States. This paper reports the first experimental yield trials of the red claw crayfish in the central United States. Two earthen ponds (0.30 and 0.31 ha) were stocked with juvenile red claw crayfish at either 3.5 or 7.0 crayfish/m². Crayfish were fed a diet of pelletized shrimp ration supplemented with corn silage. When stocked at 3.5/m₂, red claw crayfish grew from an average weight of 3.0 g to 27.0 g in 97 days; average survival was 79.6%; net yield was 653 kg/ha; and feed conversion was 1.4. When stocked at 7.0/m² red claw crayfish grew from an average weight of 4.1 g to 19.7 g in 99 days; average survival was 70.0%; net yield was 678.9 kg/ha; and feed conversion was 1.8. During the yield trial, temperatures were optimal for growth (25 to 33°C) 60% of the time. These findings are sufficiently encouraging to warrant further trials in locations with a longer growing season, in order to evaluate more fully the potential of the red claw crayfish as a candidate for aquaculture in the United States.     

Effects of Density Reduction and Supplemental Feeding on Stunted Crayfish Procambarus clarkii Populations in Earthen Ponds1

Density reduction, supplemental feeding, and a combination of two treatments were evaluated as means to alleviate stunting of red swamp crayfish Procambarus clarkii in earthen ponds. Mean total yield of crayfish in low density control ponds averaged 1,218 kg/ha and was 1.5 to 2 times higher (P≤ 0.05) than either the high density control or treatment ponds. Mean individual harvest weight of crayfish averaged 15.1 g and did not differ among treatments. Mean total yield of crayfish in ponds receiving supplemental feed was 32% higher than non-fed ponds (P≤ 0.05). Mean total yield and size of crayfish at harvest from reduced and non-reduced treatments did not differ. Density reduction and supplemental feeding implemented in early April did not increase individual crayfish weight to the commercially desirable size of 20 g.     

Feasibility of Pond Production of Largemouth Bass,Micropterus salmoides,for a Filet Market

The effects of stocking density on food‐size largemouth bass (LMB), Micropterus salmoides, production (>0.5 kg) were evaluated in a 2‐yr study by stocking LMB fingerlings (mean weight = 57 g/fish) in 0.1‐ha earthen ponds at rates of 6175, 12,350, or 18,525 fish/ha. Gross yields increased from 3989 to 9096 kg/ha as stocking density increased. No significant differences were observed in survival rates (range of 65–74%) due to density. Maximum feed consumption occurred at water temperatures of 27–30 C. Feed conversion ratio (FCR) and mean harvest weight were significantly different (P < 0.05) among densities, with the lowest FCR and the lowest mean weight found at the highest density (18,525 fish/ha). At harvest, LMB were considered to be in good condition with relative weight (W_r) values of 123–124. Dressout yield percentages were 61–62% for whole‐dressed LMB and 34–35% for shank filets. LMB grew well and reached a size adequate for targeted shank filet sizes. However, the production costs of $7.26–$9.34/kg mean that LMB production for a filet market is unlikely to be feasible. Research to lower LMB fingerling and feed costs and improved FCR would contribute to improved economic feasibility.     

Impact of hydropattern disturbance on crayfish population dynamics in the seasonal wetlands of Everglades National Park,USA

1. The natural hydropattern in the seasonally‐flooded marl prairie wetlands of Everglades National Park has been severely disrupted by human water control activities, seriously impacting higher trophic organisms, e.g. wading birds, that depend on these wetlands. Less is known about the impacts on key aquatic fauna, such as crayfish Procambarus alleni, or how these populations might respond to proposed habitat restoration strategies. 2. Under severe environmental stress, populations of burrowing crayfish are predicted to have skewed size structure, low reproductive success, low survival, and widespread dispersal. As predicted for populations in stressed habitats, crayfish density was low, small dispersing adults were dominant, juvenile abundance was low, and survival was low in habitats where the hydroperiod (duration of flooding) was short and groundwater level was lowest. 3. Crayfish dispersed during flooding, but during the drydown, they burrowed rather than sought deeper water. This dispersal strategy may be adaptive for surviving in seasonal wetlands, but this had severe consequences on survival in disturbed habitats with shortened hydroperiods. Survival in burrows during the dry season was high in the longer‐hydroperiod habitats but was zero in the short‐hydroperiod habitat where the groundwater level fell more than 1 m. 4. Long‐hydroperiod marl prairie may function as sources, whereas short‐hydroperiod habitats act as population sinks. Our study suggests that the threshold conditions for preventing mass mortality of crayfish in these wetlands are hydroperiods >7 months and groundwater levels <0.5 m below the surface during the dry season. 5. Historical (pre‐drainage) hydroperiods appear to be restricted to the longest hydroperiod areas of the marl prairie. This indicates that much of the marl prairie wetlands now function as population sinks for crayfish and other invertebrates. The historical hydropatterns need to be re‐established throughout the marl prairie wetlands to achieve the restoration goal of increasing productivity in the aquatic faunal community. Copyright © 2001 John Wiley & Sons, Ltd.     

Signal crayfish (Pacifastacus leniusculus) predation upon Atlantic salmon (Salmo salar) eggs

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Economic Evaluation of Commercial-Scale, Saltwater Pond Production of Florida Red Tilapia in Puerto Rico

An economic analysis was performed of a proposed commercial-scale 20-ha saltwater pond culture operation for Florida red tilapia in Dorado, northern Puerto Rico. The analysis was based on actual cost and production data from a commercial-scale hatchery, pilot-scale grow-out trials conducted in six 0.2-ha saltwater (avg. = 22.7 ppt) ponds at the Dorado facility and on wholesale market prices ($4.96–5.18/kg) fetched by dressed-out (gilled, gutted and scaled) product. The proposed 20-ha growout facility is comprised of 25 0.8-ha earthen ponds, each supplied with sea water, brackish well water, drainage and aeration, which account for 60.8% of the capital costs. Ponds are stocked with fingerlings (0.85 g avg. wt.) at a density of 3.0 fish/m² (30,000/ha), and are harvested at 160 and 220 d, at an average weight of 545 g for a total yield of 11,445 kg/ha per crop. Imported feed ($0.55/kg), processing and distribution ($0.50/kg) and sex-reversed fry ($0.11/fry) are the highest variable costs, accounting for 30.7%, 15.4% and 13.9%, respectively, of the total annual costs. Salaries and benefits, and depreciation represent the highest fixed costs, accounting for 8.4% and 5.5%, respectively, of the total annual costs. Under these conditions, a wholesale price of $4.55/kg results in a positive cash flow by year eight, and a breakeven price, internal rate of return (IRR), net present value (NPV) and discounted payback period (DPP) of $4.08/kg, 7.6%, ($235,717) and >10 yr, respectively, suggesting that the proposed 20-ha operation is not economically feasible under these conditions. The proposed enterprise is marginally feasible if stocking density is increased to 3.5 fish/m² while at 4.0 fish/m² economic outlook is favorable. Costs can be lowered considerably by targeting production and market variables most sensitive to profitability indices, using locally-prepared feeds, and vertically integrating hatchery and growout operations.     

Assessment of Five Shelter Types in the Production of Redclaw Crayfish Cherax quadricarinatus (Decapoda: Parastacidae) Under Earthen Pond Conditions

An experiment was designed to assess the relative performance of several shelter types on the production of redclaw crayfish Cherar quadricarinatus under earthen pond conditions. Juvenile crayfish with a mean stocking weight of 12.76 g were cultured in 24 net pens at 12.5 m² within a 0.2 ha earthen pond, and were provided with one of five shelter types or no shelter over 162 d. The various shelter types assessed were: mesh bundles, pipe stacks, car tires, elevated cement/fiber-board sheets, and cement/fiber-board sheets laid flat on the substrate. Crayfish in each pen were fed a formulated pellet diet three times each week. Treatments were assessed on the basis of crayfish growth, survival, harvest biomass and berry rate among females at harvest. There was no significant effect ( P > 0.05) of shelter type on growth; however, there was a highly significant effect ( P < 0.001) on survival with mesh bundles (75.1%), tires (51.4%), and pipe stacks (43.25%) performing significantly better than the no shelter control (15%). The consequence of equal growth and differing survival among treatments produced significant differences in harvest biomass ( P < 0.01). There were also significant differences in berry rate for the different treatments ( P = 0.002), and a significant negative correlation of berry rate on survival for those treatments where shelter was provided. This experiment showed that the shelter types provided during pond culture had a significant effect on harvested biomass, primarily through its effect on survival. The efficacy of the mesh bundle shelters may be attributable to the variability in the size of the spaces provided, and the ability of the mesh to separate many individuals relative to the overall volume of the shelter.     

Predictive equations for managing semi-intensive grow-out of a freshwater crayfish (marron), Cherax tenuimanus (Smith 1912) (Decapoda: Parastacidae), on a commercial farm

Stocking and harvest data from 45 grow-outs of the crayfish Cherax tenuimanus (Smith 1912) on a commercial farm were analysed to give predictive equations for survival, mean weight and individual weights of crayfish at harvest. Density dependence was a major factor influencing variation in survival and mean weight. Harvest mean weight decreased, and biomass increased, with density. The crayfish price ($ kg^?1) employed to estimate the market value of harvested crayfish increased with individual weight from a minimum saleable weight of 40 g. For grow-out of 0+ year-olds for 1 year, the market value was a maximum at low stocking densities of 1.5-2.0 m^?2. Further grow-out for 1 year of the unsaleable weight range (20-40 g) of 1+ year-olds, gave a harvest value which increased with stocking density. Comparison of predicted and actual cohort numbers and mean weights for a further 1 5 harvests showed no bias in prediction and a mean precision level of 16% for numbers and 11% for mean weight.     

Effects of Temperature on Feeding Activity of the White River Crayfish Procambarus acutus acutus1

Feed consumption by white river crayfish Procambarus acutus acutus in a 56-d laboratory study increased at a linear rate with water temperature over a range of 5 to 25 C. Feed consumption changed as water temperatures were cycled from 20–8–20 C (0.5 C/d) over a 68-d period and was the highest at the initial 20 C level and the lowest at 8 C. As water temperature increased, feed consumption rate increased; however, consumption never reached the initial rate at 20 C. Crayfish fed 3% and 6% of body weight were significantly larger than animals fed at 1% of body weight after 8 wk. Feed conversion ratios increased significantly with feeding rate. Based on this laboratory study, white river crayfish feed most effectively when water temperature is ≥ 15 C and the feeding rate is 3% of body weight/d.     

Effect of different dietary protein and lipid levels on growth performance, body composition of juvenile red swamp crayfish (Procambarus clarkii)

We evaluated the effect of dietary protein and lipid on growth and body composition in juvenile red swamp crayfish (Procambarus clarkii). Nine groups of crayfish were fed nine experimental diets containing three levels of protein (24, 27, and 30 %) and three levels of lipid (4, 7, and 10 %) for 8 weeks. We used a 3 × 3 factorial model with four replicates and 12 crayfish (initial average weight, 2.52 ± 0.04 g) per replicate. We measured weight gain ratio (WG), specific growth rate (SGR), and body composition. WG and SGR were significantly (P < 0.05) affected by dietary lipid but not significantly (P < 0.05) affected by dietary protein. When grouped by lipid levels, the WG of crayfish fed diets containing 7 % lipid was higher than that of crayfish fed diets containing 4 or 10 % lipid. The diet containing 30 % protein and 7 % lipid promoted the most efficient growth (WG: 483.38 %, SGR: 3.14 % day^?1). Dietary protein and lipid had no effect on condition factor or the viscous content (VC). Dietary protein, but not lipid, had a significant (P = 0.038) effect on the muscle content (MC). Crayfish fed a diet containing 27 % protein and 4 % lipid had the highest (P < 0.05) MC (16.16 %). Dietary protein levels also had a significant (P = 0.04) effect on the shell content (SC). SC was higher in crayfish fed a 30 % protein diet than in those fed 24 or 27 % protein. Proximate analysis suggested that crayfish fed a diet containing 27 % protein had a significantly higher nutritive composition than fish fed 24 or 30 % protein. Dietary protein also affected both whole body and muscle dry matter (DM) content. Similarly, both dietary protein and lipid affected whole-body crude lipid. Hepatopancreas DM, lipid content, and protein content were affected by dietary lipid. In conclusion, a diet containing 4–7 % lipid and 27 % protein with a protein to digestible energy ratio of 17–21 g protein·MJ^?1 appeared optimal.