Biological performance of African Catfish (Clarias gariepinus) cultured in recirculating system in Ibadan

This study reports the biological performance of the African Catfish (Clarias gariepinus) in commercial recirculating systems in Ibadan, Nigeria. Water temperature recorded in rearing tanks ranged from 23 to 25 °C in fingerlings systems, 23–26 °C in juvenile system and 22–28 °C in grow-out rearing tanks. SS, DO, and NH3-N concentration in rearing tanks are within tolerable range for fingerlings and juvenile systems. DO levels fell as low as 2.0 mg/l while SS rose to as much as 36 mg/l in grow-out systems. Fish mortality had positive significant correlation (p < 0.05) with nitrite concentration in cultured water (r = 0.88). The facilities operated at a mean density of 98.1 and 176.6 kg/m3 of juvenile and adult fish respectively. Density was not significantly different from one facility to another (p > 0.05). Stocking densities are 20,000–31,000; 6000–9000 and 150–300 fish/m3, while survival rates varies from 75 to 80% for fingerlings, 75–93% for juveniles and 77–88% for adult fish. Feed conversion ratio ranged from 0.60 to 0.78 for fingerlings, 1.01–2.08 for juveniles and 1.15–1.68 for adult fish while mean harvest weight for fingerling, juvenile and adult fish were 4.2, 11.2 and 981.0 g reared on the average for 28, 30 and 154 days, respectively.