Mutual interaction of salinity and dietary protein level on growth, survival and body composition of narrow clawed cray fish (Astacus leptodactylus)

In this study Astacus leptodactylus were tested for 8 week with three practical diets containing three crude protein (30, 35 and 40%) and isoenergetic level (370kcal/100 g) in fresh water and brackish water of Caspian Sea. In this test, 6 treatments were used with three replicates in 18 fiberglass tank (110 liter). Each tank had 5 narrow clawed Cray fish (mean (±SD) individual weight=17±2.3g) and totally 90 clawed Cray fish were stocking. Result indicates mean weight of Cray fish in fresh water and brackish water were 14.82 and 12.73, respectively, that were significantly different. The highest survival occurred in interaction between protein (30%) and salinity (0) (95.55%) and lowest survival occurred in protein 40 – salinity (12) that were significantly different. The highest specific growth rate (SGR), weight gain (WG), Protein Efficiency Ratio (PER), Net Protein Utilization (NPU) and lowest Feed Conversion Ratio (FCR), demonstrated that dietary (protein 30% and fresh water) which had no significantly differences. Result of this study showed that the highest protein of body composition were in practical diet containing 30% protein and 0 salinity (freshwater) that were significantly different with other treatment.