African Catfish as Biocontrol Agent of Common Carp's Adverse Effects on Water Quality

E.R. Chirwa, A. Mtethiwa, W.L. Jere and D. Kassam

Background and Objective: As common carp (Cyprinus carpio) can adversely affect water quality in aquatic ecosystems through its benthivory, its introduction is widely considered an environmental concern. This study aimed to investigate the potential use of the African catfish (Clarias gariepinus), another benthivorous fish species native to Africa as a biocontrol agent of carp’s adverse effects on water quality. Materials and Methods: The study was conducted at the National Aquaculture Center, Zomba, Malawi. Four treatments were involved: Ponds with carp (T₁), ponds with African catfish (T₂), ponds with both carp and African catfish (T₃) and ponds lacking both carp and African catfish (T₄). Results: Turbidity, dissolved solids, suspended solids, nutrients and chlorophyll-a were highest in T₁, lowest in T₄ and similar between T₂ and T₃ (p>0.05). This indicated that carp’s effects on water quality were reduced when carp were raised together with the African catfish in the same pond. Conclusion: The African catfish can be used as a biocontrol agent to mitigate the adverse effects of common carp on water quality and the farming of carp in ecosystems where the African catfish is native may not adversely affect water quality as the catfish will reduce carp’s ability to stir the bottom sediments into the water column.

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