Keywords: Nile tilapia, monoculture, sahar, polyculture, recruitment

Growth performance of Sahar (Tor putitora) and of Nile tilapia (Oreochromis niloticus) in monoculture and in combined culture was evaluated at Institute of Agriculture and Animal science (IAAS), Rampur, Chitwan Nepal using 24 m² outdoor concrete tanks (4.9 m × 4.9 m × 1.75 m). The experiment was conducted from April 19 to September 27, 2003 (161 days) in a Completely Randomized Design (CRD) with three treatments and three replications. The treatments were Sahar monoculture (T1), Nile tilapia monoculture (T2), and Sahar and Nile tilapia polyculture (T3) with stocking density of 1 fish/m², except 2 fish/m²for T3. The stocking ratio of Sahar and Nile tilapia was 1:1 in polyculture. Sahar and Nile tilapia fingerlings were stocked in the tanks with the mean weight of 26.0±2.6 gm, and 22.3±1.9 gm, respectively. The pelleted feed with 35% crude protein was given @ 3% of total body weight of fish per day. Mean daily weight gain of Nile tilapia was higher in polyculture (1.15±0.07 gm) than in the monoculture (0.83±0.14 gm). Mean survival rate (%) of tilapia was also higher in polyculture (100±0.0) than monoculture (97±2.8m). Likewise, net fish yield (gm/m²/d) was the highest in Sahar + Nile tilapia polyculture (1.6±0.2), which was the lowest (0.3±0.0) in Sahar monoculture. The recruits per tank (1745±256) was significantly higher (P<0.05) in Nile tilapia monoculture than in Sahar + Nile tilapia polyculture (2.7±0). Mean size of recruit of Nile tilapia was significantly higher (P<0.05) in Sahar + Nile tilapia polyculture (34.4±11.2) than in Nile tilapia monoculture (3.8±0.30). AFCR value was the lowest in Sahar + Nile tilapia polyculture (1.3±0.1), but the highest in Sahar monoculture (5.9±0.6). The results of this study thus has demonstrated that Sahar can be cultured in subtropical climate, which could be a suitable candidate for polyculture to control excessive recruitment of Nile tilapia.