M. Mohamadizadeh Kh - Aquaculture Department, Faculty of Agriculture and Natural Resource, Islamic Azad University, Science and Research Branch of Tehran, Tehran, Iran
M. Shamsaie - Aquaculture Department, Faculty of Agriculture and Natural Resource, Islamic Azad University, Science and Research Branch of Tehran, Tehran, Iran
Y. Abdollahtabar - Aquaculture Department, Faculty of Agriculture and Natural Resource, Islamic Azad University, Science and Research Branch of Tehran, Tehran, Iran
A. Soltani - Department of Irrigation and Reclamation engineering, Faculty of Agricultural Engineering and Technology, University of Tehran, Iran

  The effects of water current increment on rainbow trout ( Oncorhynchus mykiss ) culture were investigated   during a 35 day experiment. Fish weighing 5.5 g were stocked in aquarium tanks. Four different water speeds (0, 3.5, 7, 10.5 cm/s) were provided for each treatment in three replicates. These different currents water were provided by reusing outlet water of each culture unit. Length, weight, daily growth rate (DGR), specific growth rate (SGR), condition factor (CF) and survival rate (SR) were evaluated in each treatment. Also, the changes of NO2, NO3, NH3, NH4+, total hardness and pH were measured. The data variance analysis showed significant differences among all treatments during the first week (P<0.01). However, these results were not observed in following days. Based on Duncan’s test results, the best survival rate (97%), daily growth rate (1), SGR (6%) and average weight (24g) were achieved in 10.5 cm/s.

current speed, closed system, outlet water, rainbow trout, Iran.