| Feeding conditions of fish on early developmental stages affect their entire life cycle, four aspects that affect feeding conditions of fish on early developmental stages were studied in this paper.Trival 1:The study of early development digestive system on Elopichthys bambusa(Richardson) on morphology and histological. Study the morphology of digestive system in one month after hatching. and studing the histological using continuous biopsy techniques on 6,12,18,23,30 and 60 day-old after hatching.The result shows:excretory pore appear after 1 day hatching; the front of the intestinal formate lumen after 3 day-old, and this stage is endogenous nutrition stage.After 5 days hatching, yolk sac was completely absorbed, After 20 days hatching. Richardson begin ingestion small fish, appearing scale on belly. After 60 days hatching,the intestinal appear "Z"-type structure, intestinal wall thickening and intestinal villi developed markedly enhanced intestinal digestion and absorption, liver and pancreas is full most of the body cavity. The entire digestive system development process adapt closely to the changes in diet.Trial 2:The study of allometric model about organs that correlated to ingestion of E.bambusa.Studied the allometric model of organs that correlated to ingestion of E.bambusa that after 22 days hatching by continuous sampling,photograhing,data surveying and analysising. Result shows:head length did not appear growth inflection point. The trunk and tail fin occurred growth inflection point when its body length was 15.5,14.7mm respectively,all of them show equal growth speed with body length before inflection point, after inflection point, trunk changed to negative allometric growth, tail fin changed to positive allometric growth. Tail,body height,mouth width,eye diameterand,snout length, pectoral fin appeared growth inflection point when its body length was 15.4,13.1,10.6,13.7,14.4,9.5mm respectively,all of them growth fast before growth inflection point, after growth inflection point,positive allometric growth still abserved for tail and snout length, body height and eye diameter show equal growth speed with body length, however, mouth width and pectoral fin changde to negative allometric growth. In all character, pectoral fin appeared growth inflection point in the earliest time,marking the importance in early development stage.Trival 3:The study of ingestion rhythm and daily feeding rati of E.bambusa in early development stage. The ingestion rhythm and daily feeding rati of early larvae.late larvae and juveniles were studied by continuous sampling and analysing through 24 hours (the interval was 2 hours). Result shows:Early larvae and late larval ingested all day, no significant circadian rhythm, the fullness index was relatively high in the morning and evening. juvenile showed feeding rhythm obviously and was identified as the type of daytime feeding, the highest fullness index was appear in 19:00. The daily feeding rati of early larvae,late larvae and juveniles were 52.42%,18.72% and 9.42% respectively.Trival 4:The study of selectivity in food specification of E.bambusa.Using Cirrhinus molitorella as food of E. bambusa. In the case of free ingestion, the selectivity in food specification of 30 E.bambusas whose body length was range from 8.92cm to 30.96 cm studied length was studied.The results shows that the average body cross sectional area(BA) of Cirrhinus molitorella and mouth area of E. bambusa (MA) fitted the equation:BA=0.108+0.1741oge MA (R2=0.802, n=30); average body length(At) of Cirrhinus molitorella and E.bambusas body length(BL)fitted the equation:AL=-1.618+1.6531ogeBL (R2=0.851, n=30); range of body length of Cirrhinus molitorell (R1) and E. bambusa body length(BL)fitted the equation: RL=-5.821+2.4991oge BL(R2=0.795, n=30); the ratio between the smallest and largest body length of Cirrhinus molitorella and body length of E.bambusas fitted the equation:SR=1.419 BL-0.803(R2=0.926, n=30), LR=0.184+0.527/BL (R2=0.161, n=30). |
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