Investigation of potential production of rainbow trout in new concret ponds in Golpayegan Research Station

Abstract

The present study investigated the potential production of rainbow trout in 9 new concret ponds (19 × 2.2 × 1.5 m) in two stages including 50 gr (small size fish) and 300 gr fattened fish). In stage one (small size fish production), 3 different stock densities including 100, 115 and 130 fish/m2 with initial average weight 5 ± 1 gr and in the second stage (fattened fish), 60, 70 and 80 fish/m2 with initial average weight 65 ± 5 gr were used. Both stages carried out in a completely randomized design with 3 treatments for 75 days and 180 days during the first and second stages, respectively. In the experiment 1 (stage one), results showed that treatment with 100 fish/m2 had significantly higher weight gain and lower feed conversion ratio than other groups (P < 0.05). No significant differences were observed among the treatments for feed intake after 30 days (P > 0.05), but 130 fish/m2 had significantly the highest feed intake (100.33 gr/fish) after 75 days (P < 0.05). The highest specific growth rate and protein efficiency ratio were significantly related to 100 fish/m2 compared to other treatments (P<0.05). In the experiment 2, treatment contain 60 fish/m2 during 60, 120 and 180 rearnig days showed higher weight gain, specific growth rate (0.83, 0.91 and 0.84, respectively), protein efficiency ratio, and also lower feed conversion ratio than other treatments (P<0.05). The highest feed intake was significantly observed in 80 fish/m2 stock density after 180 days compared to other groups. In the second experiment (fattened fish) only 60 fish/m2 stock density showed the highest performance after 180 days. Therefore, the optimum stock density was 100 fish/m2 up to 50 gr (small size fish production) and 60 fish/m2 up to 300 gr (fattened fish).