Effect of dietary Spirulina platensis on fatty acid composition of rainbow trout (Oncorhynchus mykiss) fillet

This paper reports on inclusion of Spirulina platensis (SP) in rainbow trout (Oncorhynchus mykiss) fish diet and its effect on the fish tissue fatty acids (FAs) composition. Fish in triplicate groups with average initial body weight of 75 ± 0.23 g and age of about 7 months were fed a control diet with no supplements and with three experimental diets supplemented with 2.5, 5 and 7.5 weight percent (wt%) of SP for 12 weeks. At the end of experiment, the fillet FA compositions were evaluated. It was found that the composition of FAs in fish fillet was significantly (P < 0.05) affected by inclusion of SP in diets. As compared to the control sample, feeding the fish supplemented particularly with low levels of SP improved the quality of FAs by decreasing undesirable saturated FAs (SFAs) content from 20.03 to 17.93 % and increasing the level of some beneficial long-chain highly unsaturated FAs namely eicosapentaenoic acid (C20:5 n-3) from 6.47 to 7.27 %, docosapentaenoic acid (C22:5 n-3) from 1.42 to 1.56 % and docosahexaenoic acid (C22:6 n-3) from 1.26 to 1.35 %. Further increase in the SP inclusion level generally did not lead to desirable results. The SP inclusion in the fish diet had no significant impact on overall contents of n-3 and n-6 polyunsaturated FAs in fish fillet. However, the total highly unsaturated FAs (HUFAs) and n-3 HUFAs levels, UFAs/SFAs ratio and n-3/n-6 index were increased from 11.25, 10.65, 3.98 and 0.57 to 12.13, 11.56, 4.40 and 0.62 %, respectively, as a result of 5 wt% SP loading. In general, it can be concluded that SP inclusion up to 5 wt% of loading in rainbow trout culture can be beneficial in terms of FAs compositions of the fish fillet.     

A comparison of the fatty acid profiles of adult tissues,and newly hatched,fed and starved Lysmata amboinensis larvae

This study evaluated the lipid content and fatty acid (FA) profile of the hepatopancreas, ovaries and tail muscle of Lysmata amboinensis broodstock, as well as newly hatched larvae subjected to a period of starvation or feed from hatch to Zoea 2. The hepatopancreas had a high lipid content, confirming its role as a process and storage organ in L. amboinensis. Lipids were also a major component of ovarian dry weight, in agreement with reports on other crustaceans during maturation. The tail muscle, being a functional rather than a storage organ, contained low total lipids and was the tissue that closely resembled the FA profile of the newly hatched larvae. Saturated fatty acids (SFAs) and highly unsaturated fatty acids (HUFAs) were the most abundant components of the lipid profiles in broodstock and larvae. The HUFAs docosahexaenoic and eicosapentaenoic were preferentially retained during nutritional stress, confirming their importance for marine cleaner shrimp during early larval development. It appeared polyunsaturated fatty acid and HUFA requirements were met through the larval diet. The SFAs stearic and palmitic were abundant in adult tissues and larvae, whereas monounsaturated fatty acids may have been preferentially catabolized to meet energetic and metabolic larval requirements.     

Influence of egg lipids and fatty acids on egg viability, and their utilization during embryonic development of spotted wolf-fish, Anarhichas minor Olafsen

The changes in egg lipids and fatty acid compositions that occur during embryonic development of spotted wolf‐fish, Anarhichas minor, were examined by monitoring individual egg batches from the time of spawning (egg stripping) until hatching. The lipids, present as 3.7±0.1% of the wet mass of the freshly stripped eggs, contained high percentages of monoenes (monounsaturated fatty acids (MUFAs), ca. 33%) and polyenes (ca. 43%) and approximately 20% saturated fatty acids (SFAs). The fatty acid profiles were dominated by a small number of fatty acids. The major SFA was 16:0 (ca. 14%), the dominant MUFA was 18:1 n‐9 (ca. 21%), and among the polyenes, the n‐3 highly unsaturated fatty acids (HUFAs) 22:6 n‐3 docosahexaenoic acid (DHA) and 20:5 n‐3 eicosapentaenoic acid (EPA) were present in the highest concentrations (EPA, ca. 16%; DHA, ca. 19%). The n‐6 HUFA 20:4 n‐6 arachidonic acid (AA) was present as ca. 1% of the total fatty acids in the freshly stripped eggs. This resulted in an AA:EPA of ca. 0.07, which is lower than reported for eggs of many other fish species. As embryonic development progressed, the percentage contribution of AA to the total fatty acids almost doubled. There were also increases in the relative proportions of SFAs (due mainly to an increase in the percentage of 16:0 to ca. 16% at hatch) and DHA (to ca. 23%), and there was a corresponding decrease in the percentage of MUFAs (mostly brought about by a decrease in the percentage of 18:1 n‐9 to ca. 18% at hatch). The most marked changes occurred towards the end of incubation. The percentage of EPA changed little during incubation. This implies that there was selective retention of DHA, 16:0 and AA, and these fatty acids were probably incorporated into cell membranes. MUFAs, particularly 18:1 n‐9, seem to have been catabolized to provide energy for the developing embryo, and some EPA also seems to have been utilized as an energy source. Survival of eggs to the eyed stage (range ca. 10–80%) and to hatch (ca. 5–75%) was negatively correlated with the %AA, %EPA and AA:DHA of the freshly stripped eggs. There was also a negative correlation between AA:EPA and egg survival, which implies that there is not a universal requirement for a high AA:EPA to ensure high rates of survival of fish eggs.     

Dietary α‐linolenic acid affects lipid metabolism and tissue fatty acid profile and induces apoptosis in intraperitoneal adipose tissue of juvenile grass carp (Ctenopharyngodon idella)

A 56‐day feeding trial was conducted to elucidate the effects and mechanism action of dietary α‐linolenic acid (ALA, 18:3n‐3) on lipid accumulation and fatty acid profile of muscle, hepatopancreas and intraperitoneal fat (IPF) in juvenile grass carp using three isonitrogenous and isoenergetic semi‐purified diets containing 0.0% (control group), 1.0% and 2.0% ALA, respectively. The lowest intraperitoneal fat (IPF) ratio was found in 2.0% group. In the muscle, hepatopancreas and IPF, docosahexaenoic acid (DHA, 22:6n‐3) and eicosapentaenoic acid (EPA, 20:5n‐3) contents increased with the increase in dietary ALA. In the IPF, caspase 3, caspase 8 and caspase 9 showed the highest activities in 2.0% group, while the value of Bcl‐2/Bax (B‐cell leukaemia 2/Bcl‐2‐associated X protein) reached the lowest. Meanwhile, swelling of the IPF mitochondria was observed in 2.0% group. The gene expressions of fatty acid desaturase (FAD) and fatty acid elongase (ELO) in the hepatopancreas and muscle showed significantly higher levels in the treatment groups, whereas an opposite trend was existed in the IPF. Fatty acid synthase (FAS), sterol regulatory element binding protein‐1c (SREBP‐1c) in the IPF and hepatopancreas reached the lowest in 2.0% group. Overall, dietary ALA could promote n‐3 highly unsaturated fatty acids (HUFAs) synthesis and suppress the accumulation of lipid by decreasing the expression of related genes and promoting the apoptosis in IPF.     

Effects of Starvation and Feeding on Lipid Class and Fatty Acid Profile of Late Stage Mud Crab,Scylla serrata,larvae

Lipid class and fatty acid (FA) analysis were conducted on newly molted, fed, and starved zoea V and megalopa of the mud crab, Scylla serrata (S. serrata). Larvae starved for 4 d showed a substantial decrease in total FA content, from 49.67 μg/mg to 13.94 μg/mg ash‐free dry weight (AFDW) at the zoea V stage, and from 38.47 μg/mg to 10.40 μg/mg AFDW at the megalopa stage. This depletion indicates that S. serrata larvae effectively utilize stored lipid reserves for energy during periods of food deprivation. Megalopa subjected to longer starvation periods, however, did not utilize lipid as the major energy source after day 4, suggesting increased reliance on protein catabolism during prolonged starvation. At both larvae stages the major FAs were 18:1n‐9, 16:0, 20:5n‐3 (eicosapentaenoic acids, EPA), 18:3n‐3 (linolenic acid, LNA), 18:0 and 22:6n‐3 (docosahexaenoic acid, DHA) and this FA profile persisted in both fed and starved larvae. The highly unsaturated fatty acids (HUFA), EPA, DHA, and arachidonic acid (20:4n‐6, AA) were not conserved in tissue during starvation, indicating that HUFA requirements might be lower for S. serrata larvae than shown for other crustaceans. Similarly, a high level of LNA in newly molted zoea V and megalopa were rapidly depleted in unfed larvae, indicating that this FA had an important role as an energy reserve. Throughout the study, FAs from the polar lipid fraction dominated larvae tissues, while FAs from the neutral lipid constituted the largest accessible energy reserve during starvation (depleted from 23.05 to 1.23 μg/mg AFDW in zoea V, and from 19.00 to 1.27 μg/mg AFDW in megalopa). The results of this study provide new insight into lipid utilization of S. serrata larvae during development, an important step toward development of formulated diets for use in mud crab hatcheries.     

High dietary 18:2n‐6/18:3n‐3 ratio does not inhibit elongation and desaturation of 18:3n‐3 to EPA and DHA in Atlantic salmon (Salmo salar L.)

This study investigated whether retention of n‐3 fatty acids (FAs) is influenced by the levels of dietary monounsaturated (MUFA)‐, saturated (SFA)‐ and n‐6 FAs. The feeding trial used a mixture design, with rapeseed‐, palm (PO)‐ and soybean oil (SO), providing high levels of MUFA, SFA and n‐6 FAs, respectively, while 18:3n‐3, eicosapentaenoic acid (20:5n‐3) and docosahexaenoic acid (DHA, 22:6n‐3) were kept constant. Furthermore, a diet group with high SO and reduced 18:3n‐3 was included in addition to the mixture design. There were no differences in growth or proximate composition, but the PO diet gave reduced FA digestibility and increased feed conversion ratio. All diet groups had a net production of DHA, shown by retention values >100% (133%–177%). High dietary n‐6 FAs of up to 43% of FAs (18:2n‐6/18:3n‐3 ratio 8.6) did not negatively affect DHA retention, but rather had a small positive impact. High levels of substrate (dietary 18:3n‐3 at ~10% of FAs) did not enhance DHA retention compared to 5% 18:3n‐3. This is a highly significant finding for the aquaculture industry, allowing for greater flexibility in the choice of lipid sources to replace fish oil in salmon feeds.     

Effects of starvation and feeding on the fatty acid profiles of Stage I phyllosoma of the spiny lobster, Jasus edwardsii

Fatty acid analyses were conducted on newly hatched and 8‐day‐old‐starved and fed Stage I phyllosoma larvae of the spiny lobster, Jasus edwardsii. Fed animals were offered excess 1.5 mm juvenile Artemia (enriched using the alga Isochrysis galbana, Tahitian isolate, T. iso.). After 8 days, there were significant increases in larval dry weight and the proportion of lipid in fed phyllosoma, whereas these parameters decreased in starved phyllosoma. The abundance of the saturated fatty acids 16 : 0 and 18 : 0 increased in both starved and fed phyllosoma, whereas the main monounsaturated fatty acids 16 : 1n‐7, 18 : 1n‐9 and 18 : 1n‐7 increased with feeding but decreased with starvation. There were no significant differences in the relative proportions of the highly unsaturated fatty acids (HUFAs) arachidonic (AA, 20 : 4n‐6), eicosapentaenoic (EPA, 20 : 5n‐3) and docosahexanoic (DHA, 22 : 6n‐3) acids between newly hatched and starved animals, whereas quantitatively DHA decreased with starvation and feeding. The DHA/EPA ratio was significantly lower in the starved and fed phyllosoma (0.5) compared with that found in the newly hatched phyllosoma (0.9). The lipid profiles of the newly hatched, starved and fed phyllosoma contained large amounts of n‐6 fatty acids resulting in low n‐3 : n‐6 ratios (2.8, 2.7 and 1.6 respectively). The importance of these results and the ability of enriched Artemia to provide a suitable fatty acid profile for this species are discussed.     

Dietary n‐3/n‐6 ratio affects the biochemical composition of Eurasian perch (Perca fluviatilis) semen but not indicators of sperm quality

In general, the effects of dietary fatty acids (FA) on sperm quality have received less attention than egg quality, and were never studied in perch. This study investigated the effects of dietary FAs on the quality and chemical composition of sperm in Eurasian perch (Perca fluviatilis). Two experimental diets containing 16% lipids and 45% proteins were compared. The n‐3/n‐6 ratios tested were 0.2 for diet 1 (D1) and 7.0 for diet 2 (D2). No significant effects of the n‐3/n‐6 ratio were observed on the sperm characteristics, either in terms of the sperm volume (around 1.2 mL) and density, spermatozoa motility (94%) and velocity, or the sperm osmolality. All these parameters corresponded to semen of good quality in Eurasian perch. Interestingly, both the FA composition and the lipid class profile of the semen were correlated to the tested diet. However, basal levels of certain highly unsaturated FAs such as eicosapentaenoic acid, 20:5 n‐3 and docosahexaenoic acid, 22:6 n‐3, were maintained in the sperm irrespective of the diet tested. Perch semen was characterized by high levels of cholesterol, phosphatidylethanolamine and phosphatidylcholine. In conclusion, the dietary n‐3/n‐6 ratio affects the lipid composition of perch semen but not the indicators of sperm quality.     

Effect of different dietary lipid sources on growth and gonad maturation of pre‐adult female Cherax quadricarinatus (von Martens)

The effects of four dietary lipid sources (fish oil, peanut oil, soybean oil, pork lard) on growth and gonad maturation of pre‐adult female red claw crayfish, Cherax quadricarinatus, were evaluated. Performance was evaluated by weight gain, specific growth rate (SGR), survival, feed conversion ratio (FCR), gonadosomatic index (GSI), fatty acid composition, and vitellogenin (vg) gene expression. The proportion of saturated fatty acids (SFA), mono‐unsaturated fatty acids (MUFA), and poly‐unsaturated fatty acids (PUFA) in hepatopancreas varied as a result of lipid source, while differences in muscle were limited to MUFA levels. Vg expression and growth, but not GSI, differed significantly, with peak expression and optimal growth observed in red claws receiving the soybean oil diet. Conversely, diets high in EPA (20:5n3) and DHA (22:6n3) produced suboptimal results, suggesting that the importance of maturation diets with high EPA and DHA content may be exaggerated. As the dietary lipid requirements of growing and reproductively active red claw crayfish were satisfied by a plant oil that contained high levels of 18‐carbon unsaturated fatty acids, soybean oil may be an economic alternative to the expensive lipid‐fortified feed currently utilized by the aquaculture industry.     

High n‐3 HUFA levels in the diet of Atlantic salmon affect muscle and mitochondrial membrane lipids and their susceptibility to oxidative stress

Atlantic salmon were fed one of four diets with increasing levels (11–58%of total fatty acids (FAs)) of n‐3 highly unsaturated FAs (HUFAs) in order to investigate the effect on muscle and mitochondrial membrane lipids and their susceptibility to oxidative stress. The high n‐3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) groups contained lower percentages of sphingomyelin and cardiolipin in total muscle than the intermediate n‐3 HUFA group. Cardiolipin and sphingomyelin are particularly susceptible to peroxidation, and a reduced percentage of these lipids showed that mitochondrial membranes had been damaged by oxidation. The intermediate n‐3 HUFA group had the highest level of mitochondrial integrity and tendencies of lower thiobarbituric acid reactive substances (TBARS) level than the other dietary groups. The high caspase‐3 activity, in addition to casp3a and bax gene expression levels, in the n‐3 DHA group also suggests that some degree of oxidative stress had occurred. Electron microscopy images showed a higher degree of myofibre–myofibre detachment in fish fed the high HUFA diets than in fish fed the intermediate n‐3 HUFA diet. Our findings show that intermediate levels of n‐3 HUFAs in salmon diets gave the best protection against oxidative damage of mitochondrial membranes and muscle structure.     

Comparison of effects of dietary‐specific fatty acids on growth and lipid metabolism in Nile tilapia

The dominant fatty acids (FAs) in oils are often used to explain different nutritional effects of dietary oils in fish. However, the amounts of dominant FAs among oils are different, and the nutritional roles of these important FAs in fish have not been precisely compared at similar levels in feeding trials. In the present study, different amounts of palmitic acid were added to safflower oil (SO), olive oil (OO) and fish oil (FO) to obtain comparable amounts (about 550 g/kg of total FAs) of 18:2n‐6, 18:1n‐9 and 20:5n‐3 + 22:6n‐3 and subsequently fed to Nile tilapia (11.1 ± 0.01 g) for 8 weeks. The results showed similar growth among groups but FO group obtained lower fat deposition, serum ALT and AST activities, compared to OO. Lipogenesis‐related gene expressions were higher in OO group than FO group in liver, muscle and adipose tissue, but there were only few differences in these genes between SO and FO groups. Lipid catabolism genes in FO group were higher than OO and SO groups in adipose tissue, but not in muscle, and the significantly higher expressions of CPT1b and PPARα were only observed in liver. Overall, dietary 18:2n‐6, 20:5n‐3 and 22:6n‐3 were beneficial to normal growth and lipid metabolism, whereas high amount of 18:1n‐9 induced lipid deposition and liver damage in Nile tilapia.     

封闭循环流水养殖的花鳗鲡脂肪酸特征分析

为探寻封闭循环流水养殖模式下养殖的较大型(≥2 kg)花鳗鲡(Anguilla marmorata)各可食部的脂肪酸特征,利用索氏抽提法获得各部位的粗脂肪,以37种脂肪酸甲酯混标标准品为标准,气相色谱外标法检测脂肪酸的组成。检测结果显示,鱼皮中粗脂肪含量最高为26.96%,鱼肉的粗脂肪含量为10.36%;不同可食部的脂肪酸组成基本相似,饱和脂肪酸9种,单不饱和脂肪酸6种,多不饱和脂肪酸8种,饱和脂肪酸、单不饱和脂肪酸和多不饱和脂肪酸间的比例大约都为1∶3∶1,三大类脂肪酸中含量最高的分别为软脂酸C16∶0、油酸C18∶1n9c和二十二碳六烯酸C22∶6n3,油酸在不同可食部中均超过20 g/100 g总脂,C22∶6n3(DHA)在不同可食部中含量在4.42~5.59 g/100 g总脂之间。研究表明,较大型花鳗鲡是人体所需脂肪酸的良好食物来源。     

Fatty acid composition of female and male clams (Ruditapes philippinarum): energy intake and temperature reliance

We analysed the effect of temperature, coupled with food ingestion rate (IR), on the fatty acid (FA) profile of female and male clams conditioned in two groups: L (low IR at 14 and 18 °C) and H (high IR at 18 and 22 °C). Significant differences for group L, both 18L and 14L with low IR and slow gonadal development, owed to differences in energy balance between 18L clams (negative energy balance) and 14L clams (positive energy balance). Plasmalogens (DMA 18:0) and non‐methylene‐interrupted FAs might protect against reactive oxygen species and preserve the integrity of the cell membranes during food stress in 18L clams. Differences in composition for group H, both 18H and 22H with high food intake, positive energetic balance and complete and similar gonadal occupation index (GOI), probably owed to the greater energy levels at 18 °C than at 22 °C. Clams at 22 °C H increased the oxidation of short‐chained PUFA 18:3ω3 and 18:3ω6 to maintain the same GOI as 18H clams. Regarding the sexual differences, the greater accumulation of 20:5ω3 and 20:4ω6 in females might be related with oocyte maturation and release during spawning, while the greatest levels of 22:6ω3 in males might be involved in spermatocyte membranes synthesis.     

Preliminary Results on the Fatty Acid Composition of Freshwater Crayfish, Astacus astacus and Pacifastacus leniusculus, Held in Captivity

The fatty acid compositions of the tail muscle and hepatopancreas of captive noble crayfish Astacus astactus and of signal crayfish pacfastacus leniusculus were investigated. The major fatty acids in the tail muscle of A. astacus were 16:0. 18:ln-7 + 9, 20:4n–6 and 20:5n–3 and the fatty acid composition of hepatopancreas was principally 16:0, 18:In-7 + 9 and 20: ln-9+ 11. These animals had been fed marine fish (sprat and herring) for 2 mo. They were kept in a flowthrough system with gravity-fed fresh water from a nearby lake with a high concentration of calcium and pH above 8. The major fatty acids in the tail muscle of P. leniusculus were 16:0. 18:ln-7+9, 18:2n–6 and 20:5n–3, and in the hepatopancreas 16:0, 18:1n–7 + 9 and 18:2n–6. These animals had been fed mainly plant material (green peas, maize and alder leaves) in a different laboratory for a period of about 2 yr and kept in a flow-through system with ambient water of pH around 7. In A. astacus the total fatty acid content was nearly 13 times higher in the hepatopancreas than in the tail muscle, however, three fatty acids 18:0, 20:4n–6 and 20:Sn-3 were, respectively, 289, 403, and 320% more concentrated in the fatty acids of tail muscle than in the hepatopancreas. Total fatty acids of the hepatopancreas of male P. Ieniusculus was 42 times higher than in the tail muscle and was three times greater than in the hepatopancreas of A. astacus .     

Influence of one selected Tisochrysis lutea strain rich in lipids on Crassostrea gigas larval development and biochemical composition

Effects of a remarkably high overall lipid Tisochrysis lutea strain (T+) upon gross biochemical composition, fatty acid (FA), sterol and lipid class composition of Crassostrea gigas larvae were evaluated and compared with a normal strain of Tisochrysis lutea (T) and the diatom Chaetoceros neogracile (Cg). In a first experiment, the influence of different single diets (T, T+ and Cg) and a bispecific diet (TCg) was studied, whereas, effects of monospecific diets (T and T+) and bispecific diets (TCg and T+Cg) were evaluated in a second experiment. The strain T+ was very rich in triglycerides (TAG: 93–95% of total neutral lipids), saturated FA (45%), monounsaturated FA (31–33%) and total fatty acids (4.0–4.7 pg cell^?1). Larval oyster survival and growth rate were positively correlated with 18:1n‐7 and 20:1n‐7, in storage lipids (SL), and negatively related to 14:0, 18:1n‐9, 20:1n‐9, 20:4n‐6 and trans‐22‐dehydrocholesterol in membrane lipids (ML). Surprisingly, only the essential fatty acid 20:5n‐3 in SL was correlated positively with larval survival. Correlations suggest that physiological disruption by overabundance of TAG, FFA and certain fatty acids in larvae fed T+ was largely responsible for the poor performance of these larvae. ‘High‐lipid’ strains of microalgae, without regard to qualitative lipid composition, do not always improve bivalve larval performance.     

Incorporation dynamics of dietary vegetable oil fatty acids into the triacylglycerols and phospholipids of tilapia (Oreochromis niloticus) tissues (fillet,liver, visceral fat and gonads)

Tilapia (Oreochromis niloticus) previously reared on a commercial feed were fed three experimental diets with added 60 g kg⁻¹ of soybean (SO), linseed (LO) or fish oils (FO), for 6 weeks. The final bodyweight (week 6) of fish was significantly lower when feeding the vegetable oils. At 0, 2, 4 and 6 weeks, fillet, liver, visceral fat, testis and ovary triacylglycerols (TAG) and phospholipids (PL) were analysed for their fatty acid (FA) composition. The simple FA dilution model has been successfully applied to describe the incorporation of numerous dietary FAs into both tissue TAGs and PLs. Fillet PL FAs reacted more sensitively on the FAs of the SO and LO diets, when compared to the TAGs. Alterations of the hepatic TAG and PL fractions were minor and less predictable. Testicular PLs have been found to preferentially accumulate n3 FAs, in particular docosahexaenoic acid (DHA) (C22:6 n3). In contrast, ovarian TAGs showed a predominant accretion of oleic acid by the FO diet. The increased dietary unsaturation index (SO, FO) was found to augment hepatic in vivo lipid peroxidation, as assessed by the tissue malondialdehyde concentrations.     

Optimum Level of Dietary n‐3 Highly Unsaturated Fatty Acids for Juvenile Sea Cucumber,Apostichopus japonicus

A feeding trial was conducted to estimate the optimum level of dietary n‐3 highly unsaturated fatty acids (HUFAs) for juvenile sea cucumber, Apostichopus japonicas, based on growth performance and fatty acid compositions. Diets with five n‐3 HUFAs levels (0.15, 0.22, 0.33, 0.38, and 0.46%) were fed to sea cucumber juveniles (1.97 ± 0.01 g) once a day for 60 d. The sea cucumbers fed diets containing 0.22% n‐3 HUFAs showed significantly (P < 0.05) higher body weight gain, feed efficiency, and protein efficiency ratio than the sea cucumbers fed diets containing 0.15% n‐3 HUFAs, but not significantly different (P > 0.05) from those of sea cucumbers fed diets containing 0.33, 0.38, and 0.46% n‐3 HUFAs. The sea cucumbers fed diets containing 0.46% n‐3 HUFAs showed significantly (P < 0.05) higher eicosapentaenoic acid and saturated fatty acid than the sea cucumber fed diets containing 0.15% n‐3 HUFAs, but not significantly different (P > 0.05) from those of sea cucumbers fed diets containing 0.22, 0.33, and 0.38% n‐3 HUFAs. The results of growth performance and n‐3 HUFA compositions of body wall indicated that the optimum level of dietary n‐3 HUFAs for juvenile sea cucumber is between 0.22 and 0.46%.