مقايسه آب لب شور و شيرين بر عملكرد رشد و تغذيه در ماهي قزل آلاي رنگين كمان جوان

The comparison of brackish and fresh water on growth and feeding performance in juvenile raibow trout (Oncorhynchus mykiss)

In this experiment for study of growth performance of rainbow trout in two kinds of waters, two groups of juvenile rainbow trout (Oncorhynchus mykis) with the mean weight of 29.1 ±3.37 g were cultured in brackish water treatment with salinity of 2.950 PPt. and fresh water with 0.57 PPt. for 40 days respectively. Each treatment was conducted in triplicates (245 rainbow Trout fish). At the termination of experiment, the obtained data were analyzed in t-test experiment. The results showed that growth and feeding performance of Raibow trout in brackish water was increased and had significant difference (P<0.05) in comparison with fresh water. The final body weight and final body length of Raibow trout fish (82.69±5.3 g, 19.1 ±2.6 cm) in brakish water treatment had significant difference (P<0.05) in comparison with fresh water treatment (69.2±7.5 g and 17.6±3.1 cm) (P<0.05). Also in brackish water treatment, the parameters of daily growth coefficient, specific growth rate of length, velocity of length and velocity of weight in comparison with fresh water treatment was significantly increased (P<0.05). The lowest food conversion ratio (1.6), highest protein efficiency ratio (1.8) and lipid efficiency ratio (7.7) were obtained in brackish water treatment and showed significant difference (P<0.05) with fresh water. The present study showed that rainbow trout had a good ability of growth in brackish water in comparison with fresh water and growth performance of this fish in brakish water is higher.