Devil stinger is a valuable demersal scorpaenid fish while the rearing of stinger larvae still relies on live prey. This study was conducted to illustrate the development of the main digestive enzymes and digestive system during larval development of this species to provide evidence for the application of artificial feeds. Enzymatic and histological assays were conducted from 1day post hatching (dph) to 36dph in larvae. The result showed that the selected digestive enzyme activities increased significantly after 15dph. Specifically, the total trypsin activities increased significantly from 18dph to 33dph. The total pepsin and amylase activities increased significantly first and thereafter decreased significantly. The lipase activities followed the similar pattern with trypsin. With regard to the histological study, the stinger larvae open their mouth to first feeding at 3dph and turned into totally exogenous nutritional stage at 6dph. In addition, mucous membrane, rich in goblet cells, was widely distributed in oesophagus epithelium at 18dph. The height and amounts of gastric gland in cardia and main body of the stomach increased gradually with the development of stinger larvae after 15dph. The intestine length of stinger larvae was short, and goblet cell was abundant in anterior intestine after 12dph, not the posterior intestine. The ontogeny of liver and pancreas started from newly hatched stage, and the differentiation of liver was prior to pancreas. The above findings would provide evidence for the use of artificial feeds from the larval stage of stinger larvae (at least from 21dph).

Feeding trials were conducted to determine the dietary level of yeast extract (YE) for replacing dietary fish meal for evaluating whether yeast extract was superior to intact yeast as an alternative protein source for shrimp Litopenaeus vannamei. The basal diet (control, D0, containing 25% fish meal), was compared with five isonitrogenous and isoenergetic experimental diets [replacing 15% (D15), 30% (D30), 45% (D45), 60% (D60) or 100% (D100) of the fish meal in the basal diet with IYE]. The digestibility, growth and muscle composition of the shrimp were measured. The results showed that all replacement treatments displayed higher apparent digestibility of crude protein than did the control. The trypsinase activity in shrimp hepatopancreas increased significantly, whereas lipase activity decreased as the amount of dietary YE increased. The shrimp treated with D30 diet displayed the highest amylase activity in hepatopancreas. There was no significant difference in the weight gain (WG) and survival of shrimp between the control and the YE replacement treatments. Feed conversion ratio (FCR) increased as the dietary YE increased, and the FCRs of the D60 and the D100 treatments were significantly higher than that of the control (P<0.05). The growth performance among the treatments was closely related to the similarity of the essential amino acids in the diets. There was no significant difference in muscle composition of the shrimp between control and other treatments. In conclusion, up to approximately 45% of the fish meal in shrimp diet can be replaced by yeast extract in the presence of supplemental fish oil, phosphorus and calcium.

Lipid and fatty acids are among the most vital factors that provide marine fish with structural components and energy resources. The fatty acid reserves of broodstocks profoundly affect the fecundity of spaw ners as well as the quality of the new ly hatched larvae. In order to state the characteristics of lipid and fatty acid accumulation in wild-caught broodstocks of Pampus argenteus,the lipid and fatty acid content in different tissues of wild broodstocks of silver pomfret,Pampus argenteus from Mindong Seazone during the reproductive season were quantitatively investigated with the methods of chloroform-methanol and gas chromatography. The results indicated that there were significant differences in lipid content among gonad, liver and muscle. Mean total lipid levels( % in dry weight) in ovary,testis,liver and muscle were 35. 76%, 15. 11%,22. 07% and 22. 14%,respectively. Testis displayed the highest proportion of polar lipid / total lipid,w hile muscle displayed the low est proportion of polar lipid / total lipid. During the reproductive season, the total lipids and neutral lipid contents in ovary increased significantly with the development of the ovary, while the polar lipid content in muscle decreased significantly with the development of the testis. The contents of 20∶ 5n-3( EPA,2. 25- 3. 87 mg / g),22∶ 6n-3( DHA,6. 71- 13. 03 mg / g) and highly unsaturated fatty acids( HUFAs,17. 20- 29. 64 mg / g) in neutral lipid of ovary were the highest. The contents of EPA( 0. 38- 0. 27 mg /g) and DHA( 3. 12- 3. 59 mg /g) in polar lipid of testis were the highest. The n-3/n-6 ratio in gonad was significantly higher than those in liver and muscle. The essential fatty acids such as DHA were transferred among the tissues and betw een different lipid classes of the same tissue. It is therefore suggested that significant differences in total lipid content,total lipid classes and fatty acid contents( mg / g dry mass) were displayed not only among the tissues,but also betw een different lipid classes of the same tissue. The essential fatty acids were preferentially transferred from neutral lipid in muscle and liver to neutral lipid in ovary with the maturation of ovary.

wild-caught broodstocks of devil stinger Inimicus japonicas were induced with LHRH-A3 to spawn and the fertilized eggs were incubated artificially in seawater with salinity 29 at 20 ℃.The lipid compositions and fatty acid profiles of the embryos(blastula stage to tail-bud stage)and yolk-sac larvae[newly hatched,1 day post hatching(DPH),2 DPH,3 DPH(unfed)]were investigated.The results indicated that the total lipid content of devil stinger decreased from 13.85% of the blastula stage embryos to 11.66% of 3 DPH larvae.Polar lipid accounted for 72.20%-75.39% of total lipid during the early development.There was no significant difference in total lipid and polar lipid contents during embryogenesis.The total lipid and polar lipid contents declined significantly during the development of yolk-sac larvae.The neutral lipid content first increased,then decreased significantly during embryogenesis and kept stable during the development of yolk-sac larvae.DHA(22∶ 6n-3),16∶ 0,ARA(20∶ 4n-6),EPA(20∶ 5n-3),18∶ 0 and 18∶ 1n-9 were the dominant fatty acids in total lipid of embryos as well as of yolk-sac larvae.The contents(mg/gDW)of DHA,ARA and EPA in total lipid as well as in polar lipid declined significantly during the early development of the devil stinger.There was sharp declining in contents of DHA and ARA in total lipid as well as in polar lipid when the embryo developed from blastula stage to tail-bud stage.The EPA and DHA contents in neutral lipid first increased,then decreased during the early development and the peak appeared at newly-hatched larvae stage and 2 DPH larvae respectively.The ARA content in neutral lipid increased step by step during the early development.DHA and ARA to EPA,saturated fatty acids(SFAs)and poly-unsaturated fatty acids(PUFAs)to mono-unsaturated fatty acids(MUFAs)as well as N-6 PUFA to N-3PUFA were preferentially utilized in total lipid during the early embryonic development.While EPA to DHA and EPA to ARA in total lipid were preferentially utilized during the later embryogenesis and development of yolk-sac larvae.Among the SFAs,16∶ 0 to 18∶ 0 was preferentially utilized during the whole early development.Among the MUFAs,16∶ 1 to 18∶ 1 was preferentially utilized during the later embryogenesis and development of yolk-sac larvae.It was therefore suggested that DHA,EPA and ARA in polar lipid could be transferred into neutral lipid during the early development of devil stinger.And the preferential utilization of some fatty acids depended on the lipid class and the development stage of the embryo and yolk-sac larvae.

A study was undertaken to evaluate the development and metabolic substrates (carbohydrate, protein, lipid and fatty acids) dynamics during the embryonic and yolk-sac larval stages of the devil stinger, Inimicus japonicus, at different water temperatures (18, 21, 24, 27 and 30°C). The hatching time was significantly shortened when the temperature increased (P<0.05). Only 14.5% of embryos hatched at 30°C, while the hatching rate was 92.5% at 24°C. Larvae incubated at 21°C displayed the greatest survival at mouth-opened larva stage (96.5%), but the rate dropped sharply when the temperature surpassed 24°C (P<0.05). The full length and yolk-sac volume of newly hatched larva at 18°C and 30°C were significantly smaller than those at 21, 24 and 27°C. Larva at 21°C always had the largest full length during early development. The advent of mouth-opened larvae was closely related to temperature, so were the full length and yolk volume of the mouth-opened larva. As the incubation temperature declined, the mouth-opened larva obtained longer full length and less yolk remain. Lipid was, to a large extent (47.0% of the initial amount), a fuel for development when the embryo was incubated at 18°C. The depletion of protein in the embryo was significantly higher at 30°C (67.6%) than that at 21°C (31.3%). Consumption of carbohydrate was observed only in embryo at 18°C. During the development of yolk-sac larva, a lower incubation temperature induced more protein anabolism and less lipid consumption. In I. japonicus, polar lipids (PL) constituted the principal class of lipid in eggs (74.0% of the total lipid); and it was the most consumed portion during embryogenesis in all treatments. The lipid composition in mouth-opened larva was affected by the incubation temperature. The storage triglycerides (TG) tended to comprise a higher proportion in larva incubated at 30°C than in those at lower temperatures. The PL proportions in larva at 18°C and 30°C were lower than those in larvae at 21°C, 24°C and 27°C. Low concentrations of polyunsaturated fatty acid (PUFA) in embryos and larvae were correlated with increased temperatures; this indicated that the rapid development at higher temperatures was at the cost of more PUFA loss. It is concluded that 21–24°C is an appropriate range for incubation of I. japonicus eggs and larvae and that 24°C is optimal in terms of shortening the endogenous nutritional stage and improving metabolic efficiency.

Lipid as well as fatty acid is important substrate fueling normal metabolism and development of marine fish larvae.The changes in lipid characteristics and fatty acid contents of developing yolk-sac larvae of Epinephelus awoara and Trachinotus ovatus were investigated in this study.The newly hatched larvae and 1 d,2 d,3 d post hatching larvae of E.awoara and T.ovatus were sampled and their lipid contents and fatty acid profiles were assayed quantitatively.The results indicated that there were different lipid compositions between the two larvae.The neutral lipid/polar lipid ratio in E.awoara was between 0.97 and 1.22 during the development of yolk-sac larva.While in T.ovatus it was between 1.88 and 3.21.The total lipid contents of the two larvae both decreased with the development due to large consumption of neutral lipid.The dominating fatty acids in neutral lipid of E.awoara yolk-sac larva were 18∶ 1n-9,16∶ 0,DHA,16∶ 1 and 18∶ 0.While DHA,16∶ 0,18∶ 0 and 18∶ 1n-9 were the dominating in polar lipid.However,the dominating fatty acids in neutral lipid of T.ovatus larvae were 18∶ 1n-9,18∶ 2n-6,DHA,16∶ 4n-3 and 16∶ 0,and in polar lipid were DHA,16∶ 0,18∶ 1n-9 and 18∶ 2n-6.Significant decreasing of main fatty acids in neutral lipid appeared at 1 day post hatching in T.ovatus larva and at 2 days post hatching in E.awoara larva respectively.But the contents of main fatty acids in polar lipid increased significantly at 1 day post hatching in both larvae.It is therefore suggested that despite the significant differences in lipid and fatty acid profiles,the lipid consumption law was similar during the development of yolk-sac larvae of E.awoara and T.ovatus.

The basal diet(A) contains 25% fish meal as control,and four isonitrogenous isoenergic yeast extract experiment diets,which substituted 15%(B),30%(C),45%(D) and 60%(E) fish meal in basal diet,were fed to the Litopenaeus vannamei(7.50±0.13) g respectively for 42 d,then superoxide dismutase(SOD) activity and lysozyme(LSZ) activity in haemolymph and the expressions of lysozyme mRNA and Toll receptor mRNA in gill were detected.The shrimp were also challenged with Vibrio alginolyticus.The results showed that: LSZ activity in haemolymph in 15% group was significantly higher than that of control(P0.05).There was no significant difference of SOD activity in haemolymph,the expressions of lysozyme mRNA and Toll Receptor mRNA in gill between alternative groups and control group(P0.05).The cumulative mortality of 60% group at 24 h and 48 h was significant higher than that of control(P0.05),and there was no significant difference of cumulative mortality between alternative groups and control group at 72 h and 96 h(P0.05).It is therefore suggested that yeast extract can replace 45% fish meal of the diets without affecting immunity and vibrio-resistant ability of the shrimp.