THE EFFECT OF WATER SALINITY ON GROWTH AND SURVIVAL OF RUTILUS IRISII KUTUM FINGERLINGS

This research was carried out over a period of 60 days in the summer and autumn of 2005 in the Caspian Sea Aquaculture Research Station (Inland Water Aquaculture Research Center).
Fingerlings of Rutilus frisii kutum weighting one gram were transferred to fiberglass 100 liter tanks each stocked with 35 fish. The fish were divided into five groups and treated with five treatments and three replicates including, fresh water, 4ppt, 6ppt, 8ppt, and 10ppt salinity by completely randomized design. We found that different salinities did not affect the mortality rate of the fish. Comparison of food conversion ratio (FCR), special growth rate (SGR) and weight gain (WG) between control and other treatments revealed a significant difference (p£0.05). We also found that the 4ppt treatment differed meaningfully with 8ppt and 10ppt treatments in terms of FCR, SGR and WG (p£0.05) and the same was true between 6ppt and 8ppt and 10ppt treatments for the FCR, SGR and WG. The results showed that the maximum and minimum weight gain were related to 10ppt treatment (mean 58.9±2.71) and control (mean 39.1±4.73) respectively. The minimum special growth rate (0.549±0.057) was referred to the control treatment and the maximum (0.772±0.028) was seen in 10ppt salinity. The minimum average FCR (3.93±0.122) was seen in 10ppt salinity and the maximum (5.6±0.601) was observed in the control treatment. According to the results, it is suggested that the optimal salinity for fingerlings with mean weight 1gr is 8ppt and 10ppt.