ESTIMATION OF ESSENTIAL FATTY-ACID REQUIREMENTS OF COMMON CARP LARVAEUSING SEMI-PURIFIED ARTIFICIAL DIETS

Two trials were conducted with duplicate groups of (first feeding) car p larvae fed artificial dry diets based on casein and dextrin over 21 or 25 days. One control diet based on yeast was also tested. Survival, growth and fatty acid profiles of larvae were studied. In trial 1, (n -3) fatty acid requirement was estimated using diets supplemented or n ot with methyl linolenate or cod liver oil. After 21 days, the best su rvival and growth were observed in larvae fed the unsupplemented diet [(n-3) fatty acid level: 0.05%]. Survival and growth were not improved by higher levels of (n-3) fatty acids. In trial 2, (n-6) fatty acid r equirement was estimated using diets with graded levels of methyl lino leate or peanut oil. After 25 days, the best survival and growth were obtained with diets supplemented with 0.25% methyl linoleate (total (n -6) fatty acid level: 1%) or with 1.25% peanut oil (total (n-6) fatty acid level: 0.89%). Survival and growth were not improved by higher le vels of (n-6) fatty acids. Fatty acid composition of carp reflected th at of the diets and also showed that carp larvae are capable of elonga ting and desaturating linolenic acid and linoleic acid in longer chain fatty acids.