Growth, Molting and Survival Response of Juvenile Narrow Clawed Crayfish, Astacus leptodactylus, Fed Two Sources of Dietary Oils

 The influence of five pure diets of isonitrogenous and isoenergic with different ratios of Clupeidae fish oil (F) and soybean oil (S) on growth, molting and survival of narrow-clawed crayfish, Astacus leptodactylus, was evaluated during an ۸-weeks trial. As soybean oil replaced with fish oil in each treatment, gently. Test diets were inclusive F۰/S۱۰۰, F۳۰/S۷۰, F۵۰/S۵۰, F۷۰/S۳۰ and F۱۰۰/S۰ fish oil per soybean oil percent. The test organism housed in fiber-glass tanks of ۱۰۰ l capacity with flowing water and aeration in tanks are supplied. The test followed a Randomized complete design. Each treatment organized with ۶ replicates and totally ۳۰ rearing tanks involved. At the end of the trial, the crayfish offered diet containing Clupeidae fish oil (rich in n-۳ fatty acids) showed the lowest food conversion ratio and highest weight gain performance as well as molting and survival rates. In contrast, the diet containing soybean oil (rich in fatty acids n-۶) contributed least to growth and other indices. Statistical test showed the differences between this two formulated diets were significant (P<۰.۰۵). Results indicated that n-۳ series of fatty acids are required in the diet of A. leptodactylus.