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Tbe effect of water salinity on growtb and survival of RutilusIrisii kutum fingerlings

, , , This researchwas carriedout over a period of 60 days in the summerand autumnof2005 in the Caspian Sea Aquaculture Research Station (Inland Water Aquaculture Research Center). Fingerlings of Ruiilus 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 IOppt 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:50.05). We also found that the 4ppt treatment differed meaningfully with Bppt and lOppttreatments in terms of FCR, SGR and WG (pg).05) and the same was true between 6ppt and Bppt and lOppt treatments for the FCR, SGR and WG. The results showed that the maximum and minimwn weight gain were related to IOppt treatment (mean 58.9±2.71) and control (mean 39.l±4.73) respectively. The minimum special growth rate (0.549±O.057) was referred to the control treatment and the maximum (0.772±O.028) was seen in lOppt salinity .The minimum average FCR (3.93±O.l22) was seen in lOppt salinity and the maximum (5.6±O.601) was observed in the control treatment According to the results, it is suggested that the optimal salinity for fingerlings withmean weight 19ris 8ppt and lOppt