Effect of stocking densities on growth, production and survival rate of red tilapia in hapa at fish hatchery Chilya Thatta, Sindh, Pakistan

Effect of stocking density on growth, production and survival of red tilapia (Oreochromis mossambicus × O. niloticus) were conducted in hapa for 60 days at Chilya Thatta. Tilapia fry (4.5±0.02 cm, 2.0±0.01 g) were stocked into hapa (4.5x2.4x1 m). Three treatments with two replicates were used: T1-200; T2-250 and T3-300 fry/hapa. Fry were fed twice a daily with pelleted feed containing 35% protein, 5% of total biomass. After 60 days, the highest growth were determined in T1 (49.8±0.0 g) while in T3 lowest growth (29.09±0.0 g) was recorded. Production (9.56, 10.13 and 8.12 kg/m3/60days) in T1, T2 and T3 respectively were significantly different (P<0.05) to each other. Feed conversion ratio of 0.48, 0.48 and 0.49 in T1, T2 and T3, respectively not significantly different (P>0.05). Survival was significantly different among treatments (P<0.01). Highest survival (100%) was attained in T1 with lower stocking density, followed by T2 (98%) and T3 (95%). Water quality parameters recorded throughout the study period were found within the ranges for fish culture such as temperature 27.2 to 28.5 °C, dissolved oxygen 5.8 to 6.4 mg/l, pH 6.9 to 7.6, ammonia from 0.45 to 0.51 mg/l, hardness 106 to 110 ppm and nitrite 0.151 to 0.162 mg/l.