The importance of live‐feed traps – farming marine fish species

This article analyses the challenges of different live‐feed regimes for the rearing of marine finfish larvae and discusses the potential alternative live feeds to avert a future live‐feed trap. Live feeds are indispensable for the successful rearing of larvae of most marine fish species. Brine shrimps (Artemia) and rotifers comprise the live feeds of choice in marine aquaculture today. However, their nutritional composition is deficient in especially essential fatty acids, and enrichment with fish oil is needed. Fish oil is considered a limited resource owing to its origin in fully exploited wild fish stocks. Moreover, fluctuations of the natural population of Artemia will, most likely, influence future availability and prices. This emphasizes the need for optimal exploitation of available live‐feed resources and development of new sustainable alternatives, such as copepods. An array of solutions to these problems are presented to avoid a future live‐feed trap and to reduce dependence on limited resources that influence future production possibilities, species diversification, price volatility and productivity in the aquaculture sector.     

Influence of fish feed composition on oxygen utilization during decomposition of aquaculture effluents

The decomposition of the organic matter, in the form of excess feed and excreted faeces, introduced to the environment by aquaculture can endanger living organisms by lowering oxygen levels. To increase the accuracy of the oxygen utilization assessment, we developed linear (L‐MOD) and non‐linear models (NL‐MOD) for the dynamics of decomposition and accumulation of the organic matter, oxygen utilization and ammonium production. The models are based on mass‐balance stoichiometric reactions for conversion of organic matter into bacterial biomass under aerobic conditions. Organic matter is represented by a general chemical formula sensitive to protein, carbohydrate and lipid content. The mass of organic matter is expressed in chemical oxygen demand (COD) units, providing more convenient tracking of oxygen utilization. Degradable part of the organic matter is distinguished from a non‐degradable part. The model results are compared with the data sets from simulated aquaculture pond experiment.     

以大口黑鲈和大黄鱼配合饲料应用为例谈 改变鱼类营养和饲料研究范式

鱼类营养和饲料研究始于70年前并借鉴陆生动物营养研究经验形成了研究范式。在过去70年中,鱼类营养和饲料研究取得了大量的成果,这些研究成果推动了水产配合饲料技术的进步,为水产饲料产业从无到有、从小到大做出了贡献。然而,随着全球水产养殖规模的不断扩大,水产养殖发展面临的资源和环境压力日益增加,对水产饲料也提出了更高的要求。事实表明,根据一些鱼类营养和饲料研究成果所配方的饲料在养殖生产实践中往往不能取得预期的应用效果,这意味着在已有范式下取得的研究成果有时难以很好地满足现代鱼类养殖产业的需要。本文叙述了具有重要经济价值的两种肉食性鱼类大口黑鲈和大黄鱼配合饲料研发与应用的历程,指出对饲料蛋白需求的低估是限制配合饲料长期未能在大口黑鲈和大黄鱼养殖生产中应用的主要原因。早期研究报道大口黑鲈的饲料蛋白需求为400-440 g/kg,大黄鱼的饲料蛋白需求为450-470 g/kg。经过重新评估后将大口黑鲈和大黄鱼的最适饲料蛋白水平分别提高到480-510 g/kg和490-520 g/kg。在适宜的饲料蛋白水平下,投喂配合饲料的大口黑鲈和大黄鱼生长与投喂冰鲜鱼时相当。作者认为对饲料蛋白需求的低估与已有鱼类营养和饲料研究范式存在的不足有关,其表现为：（1）强调食物对鱼类生长的作用,但忽视了实验鱼遗传背景和食物以外的环境条件对生长和摄食的影响;（2）强调鱼类个体生长对评价营养需求和饲料质量的重要性,但忽视了鱼类个体生长差异并不能完全反映养殖产量和效益的事实;（3）强调生长和饲料利用效率作为鱼类营养和饲料研究评价指标的重要性,但忽视了养殖对环境和自然资源的负面影响是限制水产养殖产业可持续发展的瓶颈;（4）没有足够重视基础饲料配方在评价营养需求或饲料质量方面的影响,一些研究因基础饲料组成不当而产生没有实际意义的评价结果。针对上述问题,作者建议从概念、理论和研究方法方面对已有的范式做如下修改：（1）重视鱼类遗传背景和食物以外的环境条件对鱼类生长的影响,明确鱼类营养需求取决于其生长需求;（2）重视食物中各种营养素之间的相互作用,明确不同饲料原料在实现配方的营养平衡方面发挥着不同的作用;（3）重视对实验鱼种质和种群结构的选择,重视对照组和处理组个体生长差异的幅度对判断饲料处理效应的指示作用,重视饲料配方对渔业资源和环境等水产养殖可持续发展相关的内容的影响。经过修改后的研究范式更符合养殖生产实际,在此基础上开展研究所获得的成果也能够更好地指导配合饲料生产,为鱼类养殖产业的可持续发展提供更好的科技支撑。     

A review of diet formulation strategies and feeding systems to reduce excretory and feed wastes in aquaculture

Significant efforts should be devoted to reducing waste outputs from aquaculture operations in order to lower the environmental impacts of aquaculture in many parts of the world. Since most aquaculture wastes are ultimately from dietary origin, reduction of waste outputs should first be through improvements of diet formulation and feeding strategies. The first step in the production of feeds producing less solid waste is to eliminate poorly digestible ingredients (such as whole grain or grain by-products used as binders and fillers in the feed formulae) and to use highly digestible ingredients with good binding properties. Further reduction of solid waste can then be achieved through careful selection of the ingredients to improve apparent digestibility and the nutrient balance of the feed. Nitrogen waste outputs can be reduced through the reduction of the digestible protein to digestible energy (DP/DE) ratio of the diet. Phosphorus waste outputs can be reduced through careful selection of the ingredients and optimization of the digestible phosphorus content of the diet to meet the requirement of the fish but avoid greatly exceeding this required level. Finally, feeding practices that minimize feed wastage should be adopted since feed wastage can have a very significant impact on waste outputs from fish culture operations.     

Growth performance,feed utilization and product quality in slaughter size Atlantic salmon (Salmo salar L.) fed a diet with porcine blood meal,poultry oil and salmon oil

In a 17‐week experiment with Atlantic salmon (2.3–5.2 kg) in sea cages, a diet containing European animal by‐products and salmon oil (ABP) was compared with a control diet based on fish and plant ingredients, with respect to performance and product quality. Fish fed with the ABP diet had similar growth rates, but slightly improved feed conversion ratio (feed: gain; 1.08 versus 1.14) compared with the control. No differences were seen in fish length, live weight or condition factor. Final body composition was similar and retention of nitrogen and energy did not differ between diets. Higher DPA (C22:5 n‐3) content in the ABP diet apparently inhibited conversion of EPA (C20:5 n‐3) to DPA, resulting in higher EPA retention in muscle and whole body. Muscle and whole body DHA (C22:6 n‐3) level and n‐3 : n‐6 ratio were higher in the ABP group, corresponding with dietary levels. There were no differences in slaughter yield, quality classification, gaping score or fillet texture between diets. The feed with ABP contained less astaxanthin, possibly because of degradation catalyzed by iron in blood meal, and this resulted in lower muscle colour score and astaxanthin concentration (4.6 versus 6.4 mg kg⁻¹). A sensory test did not reveal any differences in odour, flavour, or texture.     

Study on release kinetics of nitrogen and phosphorus from fish feed

Nitrogen and Phosphorus are the major end products of fish feed loading and affect the water environment as a whole. A magnetic stirrer was used to simulate the intensity of water flow by using different stirring strengths (0, 600, 1,200 rpm), and kinetic experiments on nutrients release from different fish feed (0.2500 and 0.5000 g) were performed. Results have shown that total phosphorus (TP) increase rapidly and become stable in about 96 hr, while orthophosphate ( ), total nitrogen (TN) and ammonia nitrogen ( ) increase relatively slowly and gradually reach stable from 200, 300 and 300 hr respectively. Both released contents of unit weight fish feed (i.e. released nutrients contents) and released nutrients concentrations in the condition of stirring were higher than those in the static condition. All of the pseudo‐first‐order, pseudo‐second‐order and Elovich kinetic models can be used to describe variations of released TP, , TN and contents with time, while the pseudo‐first‐order kinetic and Elovich kinetic models give better results with R² = .66–.99 and R² = .57–.99 respectively. Variance analysis showed that both stirring strength and fish feed type have significant effects on released TP, TN and contents (p < .05), while fish feed dosage has no significant effects (p > .05). In addition, only the fish feed type does have significant effects on contents (p < .05). In sum, the release kinetics and the factors related to the release of nutrients from fish feed are essential in planning strategies of nutrient management and pollution control.     

Replacement of live feed by formulated feed: effect on the growth and spawning performance of Siamese fighting fish (Betta splendens,Regan, 1910)

Partial replacement of live feed (LF) with formulated feed (FF) was performed in Betta splendens to evaluate their growth, survival and reproductive performance. Three hundred B. splendens fry of uniform size (mean weight 0.19 g±0.01) were equally distributed in five treatment groups with each of three replicates in glass aquaria of 35 L capacity. Fish were offered diets of different ratio of LF and FF like T1 (control) – 100% LF; T2 – 75% LF, 25% FF; T3 – 50% LF, 50% FF; T4 – 25% LF, 75% FF and T5 – 100% FF. Highest (P<0.05) body weight gain (% BWG) (67.1±1.03) and specific growth rate (2.34±0.02) were observed in the T2 group. Best feed conversion ratio was also found in T2 (2.40±0.11), which was similar to T1 and T3. The highest survival rate (%) was recorded in T1, T2 and T3 groups (97±1.7), which was similar to T4 and the lowest in T5 (49±2.0). The highest gonadal weight (0.12 g±0.01) and gonadosomatic index (15.17±0.50) was observed in the T3 group during the first sampling after 63 days. No significant changes in spawning performance were observed in the second sampling after 21 days after first sampling. However, T4 group registered the highest fecundity and fertilized eggs at the end of 105 days of experiment. From the present study, it concludes that LF can be successfully replaced to the extent of 25% by FF without any detrimental effect on the growth, survival and spawning performance of B. splendens.     

Nutrient evaluation of rotifers and zooplankton: feed for marine fish larvae

The objective of this study was to examine the biochemical composition of intensively reared rotifers after enrichment with three commonly used enrichment media, Multigain, Ori‐Green and DHA‐enriched freshwater algae Chlorella, using standard enrichment protocols at a local cod larvae producer and compare it with that of natural zooplankton from Lofilab AS, a cod larvae producer using semi‐intensive rearing techniques. Unenriched rotifers were analysed to examine whether the enrichment procedures were successful in increasing the content of essential nutrients to level requirements for marine fish larvae. Neither total lipids nor proteins were affected by enrichment. Unenriched rotifers were significantly lower in highly unsaturated fatty acids (HUFAs) and significantly higher in linoleic acid (LA, C18:2, n‐6), than were zooplankton. Enrichment with Chlorella and Multigain increased the HUFAs significantly, while they were slightly reduced after enrichment with Ori‐Green. Total amino acids and mineral content were unaffected by enrichment. Zooplankton was rich in taurine and selenium, whereas rotifers were devoid of it, both prior to and after enrichment. Using zooplankton as a reference for the nutritional requirements of marine fish larvae, results from this study demonstrate that enrichment media currently in use are not effective for enhancing the nutritional quality of rotifers.     

饲料蛋白质水平对马苏大麻哈鱼幼鱼生长指标和饲料系数的影响

为了解在水温7.4～11.3℃的流水池养殖条件下马苏大麻哈鱼(Oncorhynchus masou masou)幼鱼饲料中不同蛋白质水平对其生长指标和饲料利用效率的影响,设计了5组蛋白质水平为40.40％、44.84％、50.16％、54.82％和59.03％的养殖试验,养殖期为150d.试验过程中进行了水质化学指标的...     

Relationship between feed input and sediment quality of the fish cage farms

ABSTRACT: A study was conducted to examine the variation in fish farm sediment quality with varying organic carbon input in the form of feed. In order to elucidate the seasonal variation in farm sediment quality, relation between seasonal organic carbon input, temperature and sediment quality was studied. The sediment ignition loss, redox potential and acid volatile sulfide sulfur (AVS-S) content showed a correlation with annual organic carbon input. The seasonal AVS-S content showed a significant correlation with the seasonal organic carbon input as well as temperature. Multiple regression analysis revealed that both of these factors explicated 80% of the seasonal variation in AVS-S content. Although redox conditions of the sediment could also be correlated with both the organic carbon input and temperature, the latter seemed to have a greater control. Thus, the farm sediment quality could be directly related to the annual organic carbon input to the fish farm under similar hydrographic conditions. Acid volatile sulfide sulfur content exhibited a significant correlation with both the annual as well as the seasonal organic carbon input. Therefore, AVS-S content proved to be a fairly simple and better indicator for monitoring the fish farm environment for effective farm management and sustainable aquaculture. Importance of size of pellets as a factor affecting the feed input-sediment quality relation is also demonstrated in the present study.     

Effects of water flow velocity and fish culture on net biofouling in fish cages

The effects of water flow, fish feed and cage position on net biofouling was examined in a floating cage fish farm. Fouling of 16 mm mesh net panels suspended inside and outside net cages and exposed to different treatments were monitored weekly until net apertures were completely occluded by the fouling organisms (8 weeks). Results indicate a dramatic reduction in water flow velocity throughout the fish farm due to the cage units themselves and net biofouling. The reduced water flow (<10 cm s^?1) inside net cages promoted rapid net biofouling, while rapid water flow outside the net cages (>25 cm s^?1) kept the net fouling organisms at bay. Although fish rearing in net cages with inputs of commercial pellet feed increased sessile biofouling (222% higher than outside the net cages) and non‐sessile biofouling (570% higher), the type of fish feed used did not significantly affect biofouling development. The study recommends that the geometry of serially arranged net cages, as commonly deployed in tropical tidal estuaries, be reconfigured to improve flow through in order to minimize the impact of fouling.     

Intrinsic settling rate and spatial diffusion properties of extruded fish feed pellets

Spatial and temporal feed distribution in sea cages are important factors for the farmer, fish and environment due to the strong relation to growth, feed loss, pollution and welfare. This study presents a set of experimentally derived diffusion parameters and settling rates obtained in still water from four sizes and three densities of extruded fish feed pellets commonly used in aquaculture. It was found that pellet size is positively correlated with increased diffusion and that pellet density plays a less important role. Both the size and density of pellets had a significant impact on the settling rate. Results are compared to values obtained during feed production as well as other relevant studies. The findings suggest that parameters related to hydrodynamic behaviour of groups of feed pellets may vary across different pellet types. The results may be applied to refine and parameterize pellet motion in sea cage feeding models, improving estimates of fish behaviour, growth and feed loss.     

Impact of aquaculture feed technology on fish income and poverty in Kenya

ABSTRACT

The impacts of improved agricultural technologies on smallholder households in Africa are well documented in the literature. However, the literature on the welfare impacts of aquaculture technologies, especially in the context of smallholder households, is very scanty. This paper applies the propensity score matching technique to household survey data to examine the impact of improved feed technology on fish income and poverty in Kenya. After controlling for observable household characteristics, the results indicate that improved feed technology increases aquaculture income and reduces poverty among fish farming households. Specifically, the income effect of the technology is 23–37%, with resultant poverty reduction effect of 19–23% points. Evidence from the study indicates that the likelihood of adopting improved feed in Kenya will surge with improved extension service delivery, access to government subsidized feed, and easy market access for purchasing improved feed and sale of mature fish.     

Presence and distribution of PAHs,PCBs and DDE in feed and sediments under salmon aquaculture cages in the Bay of Fundy,New Brunswick,Canada

• 1. Wastes from feed and faeces can result in the deposition of contaminants in sediments around aquaculture sites. Five types of feed pellet, a commercial fish oil and 76 sediment samples collected under and up to 100 m away from salmon aquaculture cages in the south‐western Bay of Fundy between 1998 and 2000 were analysed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and chlorinated pesticides.
• 2. Five alkylated naphthalenes (aNAs) were consistently detected in fish oil (116–180 ng g^?1, per aNA), in pellets (25–51 ng g^?1, dry weight, per aNA), and sediments (<1–45 ng g^?1, dry weight, per aNA). Other PAHs were detected at variable levels in feed or in sediments.
• 3. IUPAC congener 153 (a PCB) and p,p′‐dichlorodiphenyldichloroethylene (p,p′‐DDE) were detected more frequently than other chlorinated targets in oil (108 ng g^?1 and 176 ng g^?1 respectively), feed (<1–14 ng g^?1 and 1.7–28.2 ng g^?1 respectively) and sediments (<0.08–3 ng g^?1 and <0.5–7 ng g^?1 respectively).
• 4. Trends were observed during the first year of sediment sampling (1998), with higher organic carbon, PCBs and p,p′‐DDE levels below the cages than 50 m away. The PAHs other than aNA showed an opposite trend with distance. In 1999, levels of p,p′‐DDE and PCBs were somewhat reduced under the cages, but were detected up to 100 m away from the cages.
• 5. Levels of aNA tended to be higher at some sites in 1999 relative to 1998, reflecting variability in feed and/or differential transport or degradation of contaminants relative to the environmental background. When detected, mean levels of PCBs and DDE were 2–10 times lower in 2000 than in 1999, and PAHs were 30–40% lower in 2000 than in 1999.
• 6. Interpretation of the results is done cautiously, since the exact locations of the sites sampled is only known to an intermediate facilitating the work between farmers and scientists. Levels of contaminants are compared with international results, interpreted relative to potential toxicity, uptake from feed, from deposited sediments, and in the framework of an aquaculture decision‐support system published recently.

Copyright © 2005 John Wiley & Sons, Ltd.     

Effects of stocking density, periphyton substrate and supplemental feed on biological processes affecting water quality in earthen tilapia–prawn polyculture ponds

The technical and economic potentials of tilapia, Oreochromis niloticus (L.), and giant river prawn, Macrobrachium rosenbergii (de Man), polyculture in periphyton-based systems are under investigation in an extensive research programme. This article is a combined analysis of data from four experiments exploring the effects of periphyton, fish, prawn and feed on water quality. Factor analysis and ancova models applied to the combined dataset allowed to identify the underlying ecological processes governing the system, and construct conceptual graphic models of the periphyton–environment relationships observed. With the first factor, variability in water quality was due to autotrophic (photosynthesis and nutrient uptake) and heterotrophic (respiration and decomposition) processes affecting water quality in opposite directions. With the second factor, variability was related to decomposition on the bottom and nutrient release into the water column, algae production and sedimentation. The analysis of the relationships between both factors and the growth rates of tilapia and prawn in the different systems allowed a better understanding of the functioning of tilapia–prawn ponds, and indicates that their joint culture is technically feasible and economically viable. Therefore, this technology is recommended for poverty alleviation and nutritional security in rural Bangladesh as well as in other countries of the region.     

池塘内循环养殖模式下不同营养水平饲料对建鲤生长性能及养殖效益的影响

为探讨池塘内循环养殖模式下不同营养水平饲料对建鲤(Cyprinus carpiovar)生长性能及养殖效益的影响,以常规池塘养殖营养水平饲料为对照,提高蛋白、脂肪含量,形成3个营养水平的试验饲料,其中粗蛋白水平分别为32％、34％、38％,粗脂肪水平分别为8％、10％、11％,分别记为F1、F2、F3组,每组设3个重复...     

A review of the effects of ingredient composition and processing conditions on the physical qualities of extruded high‐energy fish feed as measured by prevailing methods

Feed comprises the biggest cost in intensive fish farming and the quality of feed is therefore important. A vast body of research has been carried out in order to investigate nutritional quality of alternative ingredients. Effects of ingredients on physical quality are seldom included in these investigations. Physical quality of feed varies with ingredient composition and processing condition and may interfere with feed intake, nutrient digestibility and therefore growth performance of the fish. In this review, physical quality of extruded, high energy feed, and how ingredient composition and processing conditions affect the quality will be addressed. Various pellet properties will be discussed and methods used to evaluate physical quality will be reviewed.     

Effects of raw corn starch levels on growth, feed utilization, plasma chemical indices and enzyme activities in juvenile yellowfin seabream Sparus latus Houttuyn

A 10‐week growth trial was conducted to evaluate the effect of raw corn starch levels on the growth, feed utilization, plasma chemical indices and metabolic enzyme activities of juvenile yellowfin seabream Sparus latus. Four semi‐purified experimental diets with different raw corn starch levels (5%, 10%, 20% and 26%) and a high‐protein control diet were prepared before the experiment and hand‐fed to triplicate groups of juvenile yellowfin seabream Sparus latus. Weight gain and specific growth rate for fish fed the diet containing 26% raw corn starch were significantly lower than those for fish fed 10% or 20% corn starch diets or the high‐protein control diet. Fish fed 10% or 20% corn starch diets had a slightly better growth performance than those fed the 5% corn starch diet. Feed efficiency ratio and protein efficiency ratio (PER) for 20% raw corn starch fed fish were the highest among all groups, although no statistically significant differences were found among the experimental groups. The high‐protein control group had a significantly lower PER value than other groups. Protein productive values for fish fed the 5% raw corn starch diet and the high‐protein control diet were significantly lower than those of fish fed the 20% raw corn starch diet, but not significantly different from the values of any other group. The values of intraperitoneal fat ratio, viscerosomatic index and condition factor, as well as body and muscle compositions, were unaffected by corn starch levels. The hepatosomatic index and liver glycogen level for fish fed 5%, 10%, 20% raw corn starch and the high‐protein control diets were equal but significantly lower compared with that of fish fed the 26% raw corn starch diet. Plasma values of the fish were not affected by various dietary treatments, except that a significantly higher plasma glucose concentration was measured in the high‐protein control group compared with the values in the other groups. There were variations in the activities of hepatic hexokinase and pyruvate kinase of the yellowfin seabream after they had been fed different dietary raw corn starch levels for 10 weeks. The overall results showed that a 20% inclusion level of raw corn starch in the diet was better utilized by juvenile yellowfin seabream than 5%, 10% or 26% levels and had a protein‐sparing effect.     

配合饲料和饵料鱼对鳜生长、胃肠结构功能及肉质的影响

为比较配合饲料与饵料鱼(湘云鲫)对鳜生长、消化系统结构功能、血浆生化指标及肌肉品质的影响,实验选取初始体重为(112.33±1.14) g的鳜210尾,随机分成2个处理,分别投喂配合饲料和湘云鲫,养殖68 d。结果显示：(1)配合饲料组的营养素沉积率显著高于湘云鲫组,增重率(WGR)、干物质饲料效率(FE)分别显著增加23.14%和30.53%,而配合饲料组鳜的干物质摄食量(FI)与湘云鲫组无显著差异。(2)配合饲料组鳜背肌的肌纤维更细,肌肉硬度、脆度、咀嚼性和胶着性显著高于湘云鲫组,并且pH降低值、滴水损失和冷冻渗出率分别降低26.67%、26.65%和24.90%,离体后丙二醛(MDA)含量显著低于湘云鲫组。(3)配合饲料组鳜血浆的甘油三酯(TG)、总胆固醇(TC)和血糖(GLU)等含量均显著高于湘云鲫组,而MDA含量则反之,高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)和HDL-C/LDL-C等指标两组无显著差异。(4)配合饲料组鳜胃蛋白酶,前肠、中肠、后肠胰蛋白酶,脂肪酶和淀粉酶活性,胃及肠道肌层厚度和绒毛高度均显著高于湘云鲫组。(5)配合饲料组鳜肠道菌群的...     

Replacing fish meal with vegetable protein sources in feed for juvenile red swamp crayfish,Procambarus clarkii: Effects of amino acids supplementation on growth and feed utilization

An 8‐week growth trial was conducted to investigate the effects of dietary fish meal replacement with a vegetable mixture of soybean meal and rapeseed meal (1:1) on growth of juvenile red swamp crayfish. Nine isonitrogenous diets were designed: V0, V34, V50, V65, V73 and V81 with six levels of vegetable proteins, and VA48, VA63 and VA78 by further adding crystalline lysine and methionine into V50, V65 and V81. Compared with V0, V34 significantly improved the specific growth rate (SGR), while V65, V73, V81 and VA78 depressed the SGR (p < .05). Feeding rate showed a decreasing trend as dietary vegetable protein level increased (p < .05), except that in VA48 group. Significantly lower FCR and higher PER were observed in V34 group, whereas all vegetable protein diets depressed the feed utilization of crayfish (p < .05). Crayfish fed with diets containing vegetable proteins showed significantly lower hepatosomatic indices and higher condition factors than the control (p < .05). Muscle lipid content was significantly (p < .05) lowered in V81 group, but not in VA78 group. The results suggested that 338 g/kg vegetable protein improved growth performance of crayfish. Excessive vegetable protein depressed the growth of crayfish, which could be prevented by lysine and methionine supplementation except for the all vegetable protein diets.