An Appraisal of Introduced African Catfish Clarias gariepinus (Burchell 1822) in India: Invasion and Risks

Production trend, food and feeding, reproduction and distribution of clandestinely introduced African catfish Clarias gariepinus was studied in 419 grow out ponds. Hybrid African catfish was found more popular owing to its fast growth and because of recycling it with chicken and slaughterhouse wastes. The growth, survival and production of the fish was found to vary largely due to variations in stocking density, pond sizes, feeding types, level of cannibalism, predation, genetic lineage. The calculated growth of the fish ranged 23.52±2.8 g month-1 (minimum) in some grow-out farms while it was 223.14±18.8 g month-1 (maximum) in others. The computation of the grow-out farms as per the feed types revealed that 7% grow-out farms subsisted on naturally available pond food; while 29% farms, the fish was fed with slaughterhouse waste; in 32% farms, chicken waste was used as feed while in 11% cases fish waste material was provided and 21% ponds, the farmers used improvised convention feed or commercial pellet feed. The fish was found to possess human health risk as assessed for heavy metal contamination of lead (Pb) in chicken waste fed cultures. C. gariepinus was assessed as generalised piscivore, and invasive species therefore, we have attempted to understand the impacts associated with unauthorised introduction and spread of the fish in India. The highly carnivorous habit, tolerance to wide habitat and harsh environment and natural breeding of the fish warranted for its invasiveness which were attributable to the biodiversity loss. The issues associated with the culture and spread of the fish is discussed in this paper.