Assessment of dietary lecithin and cholesterol requirements of mud crab, Scylla serrata, megalopa using semi-purified microbound diets

The effects of varying dietary lecithin and cholesterol levels on growth, development and survival of mud crab, Scylla serrata, megalopa were evaluated using six semi‐purified, microbound diets formulated to be iso‐energetic and containing three levels of supplemental lecithin (0, 20 and 40 g kg⁻¹ diet dry weight) and two levels of supplemental cholesterol (0 and 7 g kg⁻¹ diet dry weight). Fifteen megalopa were reared individually in each treatment and the nutritional value of diets was assessed on basis of mean dry weight and mean carapace width of newly settled first crab stage, as well as development time to the first crab stage and overall survival. A significant interaction between supplemental dietary lecithin and supplemental dietary cholesterol was found for final mean dry weight of newly settled crabs, and highest survival (60%) was recorded for megalopa fed diets containing the highest levels of dietary lecithin (39.7–44.1 g kg⁻¹) (diet 5 and 6) regardless of whether diets were supplemented with cholesterol; this rate of survival was identical to that of megalopa fed live Artemia nauplii. The results indicate that supplemental dietary cholesterol may not be essential for mud crab megalopa when fed diets containing sufficient levels of supplemental dietary phospholipids.     

Effects of ammonia and nitrite on survival, growth and moulting in juvenile tiger crab, Orithyia sinica (Linnaeus)

The effects of ammonia and nitrite on survival, growth and moulting were investigated in juvenile tiger crab, Orithyia sinica (carapace length 3.91±0.15 mm, carapace width 3.84±0.23 mm, n=440), after 30 days exposure to ammonia‐N (0, 20, 50, 100 and 150 mg L^?1) and nitrite‐N (0, 50, 100, 150, 200 and 250 mg L^?1) using a continuous flow system. Survival rates of tiger crab exposed to ammonia and nitrite decreased linearly with the exposure time and concentration. The growth rate of tiger crab exposed to 50, 100 and 150 mg L^?1 ammonia was significantly lower than that of control crabs. The growth rate of tiger crab exposed to nitrite decreased at 150, 200 and 250 mg L^?1 nitrite. During the ammonia and nitrite exposure, the intermoult period of the juveniles of tiger crab O. sinica was shortened between the first and second moult, and the number of moulting of crabs exposed to a higher concentration were significantly higher than that of control crabs.     

Dietary astaxanthin supplementation for hatchery‐cultured red king crab,Paralithodes camtschaticus,juveniles

We conducted large‐scale production trials in Seward, Alaska, USA to investigate effects of dietary astaxanthin supplementation on survival, growth and shell colouration of recently settled juvenile (C1–C4) red king crabs (Paralithodes camtschaticus). We supplemented a control diet of commercial crustacean feeds with astaxanthin, and fed these diets to juvenile king crabs at densities of 2000 and 4000 crabs m^?2 for 56 days. We assessed survival and growth by counting crabs and individually measuring carapace width and weighing crabs at the start and end of the experiment, and quantified crab colour (hue, saturation, brightness) in digital photographs. Diets containing astaxanthin had higher survival, suggesting that astaxanthin may provide nutritional or immune system benefits. Crabs had lower hue, higher saturation and lower brightness values when fed diets containing astaxanthin, suggesting that red king crab colouration is plastic and responds to diet. Astaxanthin is likely an important dietary component for hatchery or laboratory reared red king crab juveniles, and should be considered for aquaculture and other rearing of this and possibly other crustacean species.     

饲料蛋白质水平对拟穴青蟹幼蟹生长性能、体成分和消化酶活性的影响

用蛋白质水平分别为31.45%,36.37%,41.55%,46.13%,51.72%和56.86%的6种等能饲料,对初始体重为(11.86?0.11)mg的拟穴青蟹(Scylla paramamosain)幼蟹进行为期3周的养殖实验,考察饲料蛋白质水平对拟穴青蟹幼蟹生长性能、体成分以及消化酶活性的影响,以期获得拟穴青蟹幼蟹饲料蛋白质的适宜添加量。结果表明,饲料蛋白质水平对拟穴青蟹幼蟹的成活率影响不显著(P0.05);幼蟹的增重率和特定生长率随饲料蛋白质水平的提高先显著升高(P0.05)后稍有下降,最大值出现在蛋白质水平为51.72%的实验组;随着饲料蛋白质水平的提高,幼蟹粗蛋白质含量显著升高(P0.05)后趋于稳定,粗脂肪含量显著降低(P0.05),灰分含量先显著升高(P0.05)后显著降低(P0.05),水分含量则没有显著变化(P0.05);随着饲料蛋白质水平的提高,幼蟹蛋白酶活性显著升高(P0.05),淀粉酶活性显著降低(P0.05),各组脂肪酶活性也有显著差异(P0.05),但没有明显的变化规律。本研究条件下,饲料蛋白质水平在41.55%~56.86%,拟穴青蟹幼蟹均表现出较好的生长率,增重率和蛋白质水平的回归分析表明,幼蟹饲料蛋白质适宜水平为49.03%。     

A Standard Reference Diet for Crustacean Nutrition Research.: V. Growth and Survival of Juvenile Dungeness Crabs Cancer magister

An experiment was conducted to measure the survival and growth of juvenile Dungeness crabs ( Cancer magister ) when fed purified crustacean diets in intensive laboratory culture. Wild-caught juvenile crabs were held individually and fed either a casein-based diet previously used for lobster experimentation (diet BML-81 S), a crab protein-based diet (HFX-CRD-84), or a closed-formula commercial fish (trout) diet. Diets BML-81 S and HFX-CRD-84 have been proposed as possible general crustacean reference diets. The crab protein-based diet appeared to be more attractive to the crabs, but after a 90 day experimental period there were no significant differences ( P < 0.01) in growth or survival between crabs fed the proposed reference diets; however, survival on the trout diet was significantly reduced. Results are discussed in relation to the rearing conditions and the composition and physical characteristics of the diets.     

Effect of different forms of Artemia biomass as a food source on survival,molting and growth rate of mud crab (Scylla paramamosain)

An experiment was conducted to evaluate the effect of different forms of Artemia biomass as a food source on survival, molting and growth rate of mud crab Scylla paramamosain. Instar 1 crablets with a mean weight of 0.0082 ± 0.0007 g were reared both individually and communally and fed with different diets consisting of fresh shrimp meat (control feed), live Artemia biomass, frozen Artemia biomass and a dried Artemia‐based formulated feed for 40 days. The highest survival was obtained for crablets receiving live Artemia (92.5% and 75.8%) followed by the groups fed with frozen biomass (90.0% and 47.5%), the control feed (72.5% and 24.2%) and the dried Artemia‐based diet (60.0% and 21.7%) for individual and communal cultures, respectively. The intermolt period, the total number of moltings and the growth rate, which were determined on individually reared crabs, showed the same pattern as for survival. The results suggest that crab performance decreased in the following order: live Artemia>frozen Artemia > fresh shrimp meat > dried Artemia‐based formulated feed. Live Artemia biomass proved an ideal feed for nursery of Scylla paramamosain crabs. Frozen Artemia biomass may be an alternative in times of shortage. Our findings illustrate the high potential for local utilization of Artemia biomass in Vietnam for reliable production of mud crab juveniles.     

Effects of dietary phospholipids levels on growth performance,lipid metabolism,and antioxidant capacity of the early juvenile green mud crab,Scylla paramamosain (Estampador)

Four iso‐nitrogenous and iso‐lipidic diets were designed to investigate the effects of dietary phospholipids (PL) levels (with 0%, 1%, 2%, and 4% PL supplementation) on growth performance, lipid metabolism, and antioxidant capacity in early juvenile green mud crab (Scylla paramamosain). There were three replicates of 28 crabs (initial body weight from 42.02 to 42.44 mg) for each diet treatment, and growth trial lasted for 8 weeks. At the end of the growth trial, there was no significant difference in survival among all treatments. Crabs fed diet with 2% PL obtained highest weight gain (WG) and specific growth rate than other crabs. The molting frequency was not affected by different dietary PL addition. Besides, the contents of whole body lipid and long chain highly unsaturated fatty acids significantly increased with elevating dietary PL levels. In the hepatopancreas, crabs fed diet with 0% PL had significantly higher malondialdehyde concentration than other crabs. And crabs fed diet with 2% PL obtained significantly higher superoxide dismutase activity than crabs fed diets with 0% and 4% PL. Moreover, the mRNA expression of Na⁺/K⁺‐ATPase was significantly down‐regulated with dietary PL supplementation over 2%. Based on the second order polynomial regression analysis of WG, 2.37% dietary PL level was the optimal demand for early juvenile S. paramamosain. Moreover, we found crabs fed diet with 2% PL obtained better antioxidant capacity than other crabs.     

Development of nursery culture techniques for the mud crab Scylla paramamosain (Estampador)

Cannibalism is one of the main causes of mortality in the culture of the mud crab Scylla paramamosain, particularly in the early post‐larval and juvenile stages when the densities of hatchery‐reared crabs may be very high before stocking into ponds or release into the wild for stock enhancement. In a series of experiments investigating cannibalism mitigation, the influence of stocking density, the effectiveness of sand substrate, brick and shell shelters and feed type were compared in culture of crabs from instar 1 for short nursery periods of 15–30 days. Inclusion of brick and shell shelters significantly increased survival over sand substrate alone. However, inclusion of shelters did not affect growth rates. In scaled‐up nursery production in lined‐ponds, with shelters, live Artemia biomass and fresh chopped shrimp or tilapia were found to be equally effective feeds for juvenile crabs stocked at a density of 70 m⁻² from instar 1 and grown for 30 days [52–66% survival, 21.6–24.6 mm carapace width (CW)]. In an extended nursery period for a further 30 days, crabs of 22 mm CW, stocked at 30 m⁻² in the same ponds, attained a final size of 34.5–36.2 mm CW with a survival of 64.3–67.0% using the same feeds.     

Effect of dietary cholesterol levels on growth performance,body composition and gene expression of juvenile mud crab Scylla paramamosain

A 56‐day feeding trial was conducted to investigate the effect of dietary cholesterol (CHOL) levels on growth performance, body composition and gene expression of juvenile mud crab (Scylla paramamosain). Four isonitrogenous and isoenergetic diets were formulated with 0.4%, 0.8%, 1.2% and 1.6% CHOL supplemented, and the final dietary CHOL concentrations were 0.72%, 1.11%, 1.49% and 1.83% respectively. Each dietary treatment was performed with three replicates (28 crabs per replicate, initial body weight 0.04 g). At the termination of the experiment, although the survival had no statistic difference in all treatments, the mud crabs fed the lowest CHOL diet had the lowest survival rate. The weight gain (WG) of mud crab significantly increased with dietary CHOL level up to 1.11% and then significantly decreased with dietary CHOL level further increased. The total‐cholesterol (T‐CHOL) content in whole body had an increasing trend with the dietary CHOL level increased. Besides, dietary CHOL supplement generally increased the hepatic superoxide dismutase (SOD) activity, and the mud crabs fed diets CHOL1.11 and CHOL1.49 showed significantly higher value than those fed other diets. The hepatic aspartate aminotransferase (AST) activity decreased slightly with dietary CHOL level up to 1.11% and then significantly increased with CHOL level further increased. The mRNA expression of ecdysone receptor (EcR) gene in the eyestalk obviously increased with dietary CHOL level up to 1.11% and then significantly decreased with dietary CHOL further increased. These results suggested that about 1.11% dietary CHOL seem fulfil to maintain good growth performance and healthy condition for juvenile S. paramamosain.     

Effects of dietary DHA/EPA ratios on growth performance,survival and fatty acid composition of juvenile swimming crab (Portunus trituberculatus)

This study was conducted to investigate the effects of dietary docosahexaenoic to eicosapentaenoic acid (DHA/EPA) ratios on growth performance, survival and fatty acid composition of juvenile swimming crab (Portunus trituberculatus). Four isonitrogenous and isoenergetic experimental diets were formulated to contain different DHA/EPA ratios (0.70, 0.84, 1.06 and 1.25). There were three replicates (15 crabs per replicate) for each diet treatment. The crabs were fed (about 6–8% body weight) twice daily for 8 weeks. A good growth performance and feed utilization were observed in swimming crabs fed the diets with DHA/EPA ratios of 0.70 and 0.84. Crabs fed diet with 0.70 DHA/EPA ratio showed a significantly higher weight gain (WG) compared with the crabs fed the diet with DHA/EPA ratio of 1.25 (P < 0.05). The result of this study showed that the survival increased with decreasing the ratio of DHA/EPA. The DHA/EPA ratios in polar lipid from tissues were influenced by the dietary DHA/EPA ratios. Results of this study indicated that the growth performance and survival of juvenile swimming crab are correlated to the DHA/EPA ratio in the diets, and the best growth performance and survival were achieved with the ratios of 0.70–0.84.     

The effects of supplemental dietary cholesterol on growth, development and survival of mud crab, Scylla serrata, megalopa fed semi-purified diets

The effects of varying levels of dietary cholesterol on growth, development time and survival of mud crab, Scylla serrata megalopa were investigated using semi-purified microbound diets (MBD). Five iso-energetic diets containing different level of cholesterol ranging from 0.14% to 1% of dry weight of the diet were tested. Fifteen megalopa were reared individually for each dietary treatment, and development time and survival were recorded on a daily basis. More than 25% of megalopa from all treatments were able to metamorphose into the first crab stage, suggesting that the endogenous level of cholesterol in the basal diet (0.14%) was sufficient to support development of the megalopa stage of this species. Widest mean carapace width (3.53 ± 0.08 mm) and highest mean dry weight (2.11 ± 0.22 mg) were recorded for juveniles that molted from megalopa fed live Artemia, whereas no megalopa in the unfed control treatment metamorphosed into crabs. The average development time from megalopa to the juvenile crab stage varied between the treatments, where megalopa fed live Artemia or MBD containing 0.2%, 0.4% or 0.8% total cholesterol showed the most synchronized molting (between 8.0 and 9.9 days). Longest development time was recorded for the megalopa fed diets containing 0.14% or 1% total cholesterol (both 11 days). Highest survival (74.3%) was recorded for the megalopa fed a diet containing 0.8% cholesterol. The results of this study are valuable in research to develop formulated diets for mud crab larvae as a replacement for live food in hatchery culture.     

Comparative performance of hatchery-reared and wild Scylla paramamosain (Estampador, 1949) in pond culture

The performance of hatchery‐reared juveniles either in aquaculture grow‐out systems or stock enhancement is likely to be dependent on a range of factors during the hatchery phase of production. With recent progress in the development of hatchery systems for the mud crabs Scylla spp., there is growing interest in evaluation of the quality of hatchery‐reared juveniles relative to wild seed crabs as currently used in aquaculture. Hatchery‐reared and wild‐collected Scylla paramamosain juveniles were stocked either together in ponds or separately. All crabs were tagged with microwire‐coded tags, so that origin could be determined in the mixed groups. Preliminary validation demonstrated that tagging did not affect survival or growth, with a tag retention of 94%. After 106 days of culture, there was no significant difference in survival at harvest between the two sources of crabs. The wild juvenile crabs had a significantly higher initial weight:carapace width (CW) ratio compared with those from the hatchery, indicating a difference in condition. However, where crabs were stocked separately, the hatchery‐reared animals exhibited significantly faster growth than those collected from the wild, both in terms of specific growth rate and CW increase per month. However, in the mixed ponds, where there was competition with wild crabs, there was no significant difference in growth rate between crabs from the two sources. Overall, the results demonstrate that the growth performance of hatchery‐reared S. paramamosain can at least equal that of wild‐collected seed crabs in ponds culture.     

Experimental nursery culture of the mud crab <Emphasis Type="Italic">Scylla paramamosain</Emphasis> (Estampador) in China

For the improvement of nursery culture of the mud crab Scylla paramamosain, a special nursery facility was purposely designed and built. This facility consists of nursery ponds (areas of 20, 50, and 120 m², respectively) and a seed collecting pond connected to each nursery pond. There were 140 nursery facility units in operation for large-scale juvenile crab production. A series of experiments were carried out using the facility to investigate the effects of the age of megalopae, stocking density, and culture duration of both megalopae and first-stage crabs on the survival of megalopae and early juveniles of S. paramamosain. The results showed that when megalopae were stocked at a density between 3,000 and 5,000 ind m⁻² and reared to reach the first-stage crabs, a survival rate of up to 50% could be achieved. When the first-stage juvenile crabs were stocked at a density between 2,000 and 3,000 ind m⁻², their survival was more than 50% after 14 days of culture.     

SEM observations on larval shell morphology of Manila clam Ruditapes philippinarum and their utility

Manila clam Ruditapes philippinarum is common and abundant on Japanese tidal flats, forming a commercially important clam fishery. However, annual catches of Manila clam have decreased drastically since 1975?C1985. To study larval recruitment processes of Manila clam, we carried out scanning electron microscopy (SEM) observations on larval and juvenile shells of clams reared at 20 and 24?°C. There was no significant difference in final shell length of trochophores between 20 and 24?°C. However, the larval duration was much longer and the shell length of settled size of pediveligers was much larger for clams reared at 20?°C than those reared at 24?°C. These findings suggest that larval duration and growth, as well as settlement size, may vary markedly depending on temperature (and probably on season). The larval shell morphology of Manila clam can provide essential information about larval recruitment processes.     

Marine microalgae as dietary supplements in the culture of juvenile Chinese horseshoe crabs,Tachypleus tridentatus (Xiphosura)

Five treatments (short‐neck clam Ruditapes philippinarum and four formulated diets with the green microalgae Dunaliella tertiolecta or the golden‐brown microalgae Isochrysis galbana in the ratio (dw/dw) of 5% or 10% to that of clam meat) were used to investigate the growth performance and haemolymph quality of juvenile Chinese horseshoe crabs Tachypleus tridentatus under laboratory culture. At the end of the 12‐week study, various growth and moulting indicators as well as haemolymph biochemical parameters did not show any significant differences among the treatments. Significantly higher percentages of haemolymph amoebocyte viability and granular‐spherical amoebocyte state were noted in both 5% and 10% I. galbana‐supplemented diets compared to that of clam meat. However, the percentages of these two haemolymph parameters in juveniles fed with D. tertiolecta decreased significantly at the end of the experiment. Such differences were attributed to the presence of polyunsaturated fatty acid (PUFA), notably eicosapentaenoic acid (EPA), in I. galbana that was absent in D. tertiolecta and clam meat. Like many marine invertebrates, juvenile horseshoe crabs do not naturally obtain sufficient PUFAs from their diets to meet developmental and physiological needs; hence, supplementing microalgae with high levels of EPA in a protein‐rich diet boosts immune competence and the health status of juvenile horseshoe crabs while under culture.     

不同饵料对短蛸生长的影响

在盐度28~30、水温23.6~25.8℃下,将54只初始体质量(34.82±3.79)g的健康短蛸放入500mL矿泉水瓶中,瓶体周身均匀钻直径5mm小孔约80个,每瓶1只,悬挂在4.1m×6.6m×1.4m养殖池中,投喂菲律宾蛤仔、缢蛏和肉球近方蟹3种饵料,每种饵料3个平行组,比较分析3种饵料对短蛸生长的影响。28d的饲养表明,3个饵料组的成活率均为100%,但投喂肉球近方蟹的短蛸特定生长率(1.67%/d)和饵料转化效率(33.46%)显著高于投喂缢蛏(1.33%/d,14.01%)和菲律宾蛤仔(1.31%/d,19.57%)的短蛸(P0.05)。试验结果表明,蟹类是短蛸养成阶段较理想的饵料。     

Effect of dietary lipid levels on growth performance,fatty acid profile and enzymatic activity of juvenile swimming crab,Portunus trituberculatus

The main objective of this investigation was to study the lipid requirements of the early juvenile (C1) swimming crab (Portunus trituberculatus) based on growth performance, survival, moulting and fatty acid profile. Four test diets were formulated with graded lipid levels (3.63%, 6.70%, 10.72% and 13.91%). Each diet was fed to 4 replicates of crabs (30 crabs per replicate initial weight (8.4 ± 0.1 mg). In this study, crabs fed diets with 13.91% lipid had significantly (p < 0.05) higher survival than crabs fed with 3.63% lipid, but no significant (p > 0.05) improvement of survival was observed when dietary lipid increase from 6.70% to 13.91%. Crabs fed diets with 10.72% and 13.91% lipid had significant higher weight gain(WG) than crabs fed with 3.63% lipid. While crabs fed with diets containing 6.70%, 10.72% and 13.91% lipid showed no significant (p > 0.05) difference in weight gain(WG). Moreover, the lowest moulting number was observed in crabs fed diets with 3.63% lipid, but there was no significant difference (p > 0.05) among other groups. The content of LC‐PUFA and DHA in the crabs fed diets with 3.63% lipid was significant (p < 0.05) lower compared to other groups. But there was no significant (p > 0.05) difference in EPA and ARA content among all groups. The activity of lipase increased as dietary lipid level increased (from 6.70% to 10.72%). However, beyond 10.72%, a significant (p < 0.05) decreased in lipase activity was observed. The regression analysis of weight gain data indicated that crab fed diet containing 10.47% lipid level is considered as optimum lipid level for its maximum growth and moulting process.     

Extension of nursery culture of Scylla serrata (Forsskål) juveniles in net cages and ponds

To address the preference of mud crab farmers for larger size Scylla serrata juveniles (5.0–10 g body weight or BW; 3.0–5.0 cm internal carapace width or ICW), a study was conducted to compare the growth and survival of crab juveniles (2.0–5.0 g BW; 1.0–3.0 cm ICW) produced a month after stocking of megalopae in net cages when reared further in net cages installed in earthen ponds or when stocked directly in earthen ponds. In a 3 × 2 factorial experiment, three stocking densities (1, 3 and 5 ind m⁻²), two types of rearing units (net cages or earthen pond) were used. Megalopae were grown to juvenile stage for 30 days in net cages set inside a 4000 m² brackishwater pond and fed brown mussel (Modiolus metcalfei). Crab juveniles were then transferred to either net cages (mesh size of 1.0 mm) or earthen ponds at three stocking densities. After 1 month, no interaction between stocking density and rearing unit was detected so data were pooled for each stocking density and rearing unit. There were no significant differences in the growth or survival rate of crab juveniles across stocking density treatments. Regardless of stocking density, survival in net cages was higher (77.11±6.62%) than in ponds (40.41±3.59%). Growth, however, was significantly higher for crab juveniles reared in earthen ponds. The range of mean BW of 10.5–16.0 g and an ICW of 3.78–4.33 cm obtained are within the size range preferred by mud crab operators for stocking grow‐out ponds.     

Effect of dietary lipids and vitamin E on growth performance,body composition,anti‐oxidative ability and resistance to Aeromonas hydrophila challenge of juvenile Chinese mitten crab Eriocheir sinensis

Vitamin E supplement is important in protecting lipid oxidation and enhancing immunity of aquatic animals. A 10‐week feeding trial was conducted to evaluate the effect of dietary lipid and vitamin E on juvenile Chinese mitten crab Eriocheir sinensis. The experimental diets included three levels of vitamin E (0, 100 and 300 mg kg^?1) and two levels of lipid (6% and 9%). The 9% lipid diet significantly enhanced the body lipid of crabs compared with the 6% lipid diet. The vitamin E concentration of hepatopancreas increased with the increase in vitamin E in the diets regardless of dietary lipid levels. The hepatopancreas fatty acids, especially polyunsaturated fatty acid and highly unsaturated fatty acid, were significantly enhanced by vitamin E supplement or 9% dietary lipid. Vitamin E supplement significantly increased the total antioxidant capacity, superoxide dismutase, lysozyme and phenoloxidase activities of crabs compared with those fed the diets without vitamin E supplement. The hepatopancreas malondialdehyde of crabs fed 100 mg vitamin E kg^?1 was significantly lower than those fed 0 or 300 mg vitamin E kg^?1. The phenoloxidase activity of crabs fed the 9% lipid diet was significantly higher than those fed 6% lipid, irrespective of vitamin E levels. Vitamin E supplementation increased the bacterial resistance of juvenile crab. This study indicates that dietary lipid and vitamin E supplement do not affect crab growth and survival, but vitatmin E supplement at 100 mg kg^?1 can enhance immunity and antioxidant capacity of crab fed 6% or 9% dietary lipids.     

Effects of dietary phospholipids and highly unsaturated fatty acids on the precocity,survival, growth and hepatic lipid composition of juvenile Chinese mitten crab,Eriocheir sinensis (H. Milne‐Edwards)

Precocious puberty is one of the major constraints to the further development of Chinese mitten crab (Eriocheir sinensis) farming industry. Although dietary phospholipids (PL) and highly unsaturated fatty acids (HUFA) supplementation have been shown to enhance the growth of larval E. sinensis in other studies, it is still unknown whether this also leads to a higher precocity rate for juvenile E. sinensis. This study was conducted to investigate the effects of dietary PL and HUFA on precocity, survival, growth and hepatic lipid composition of juvenile E. sinensis. Two diets were formulated with PL [3.95% dry weight (DW)] and HUFA (0.98% DW) supplementation (diet A) and without PL and HUFA supplementation (diet B) and fed to juvenile E. sinensis. Although dietary PL and HUFA levels did not significantly affect the survival and growth performance of juvenile E. sinensis, compared with crabs fed diet A, a higher precocity rate was found among juvenile E. sinensis fed diet B (P=0.051). A higher total lipid content, but significantly lower levels of HUFA and PL (P<0.05) were found in the hepatopancreas of crabs fed diet B than in those fed diet A. Meanwhile, the precocious females had significantly lower hepatosomatic index, arachidonic acid (20:4n‐6), eicosapentaenoic acid (20:5n‐3) and docosahexaenoic acid (22:6n‐3) contents in their hepatopancreas when compared with that of the normal immature juveniles (P<0.05). The results suggest that the occurrence of precocious puberty among farmed juvenile E. sinensis could be reduced by the inclusion of appropriate level of dietary PL and HUFA.