Health indices of African Catfish (Clarias gariepinus) inhabiting selected polluted streams in Ibadan, Oyo State, Nigeria

Claria gariepinus in polluted streams

Abstract

Environmental pollutants, such as heavy metal contamination in water sources, especially groundwater and surface water, have been documented to have various health impacts on humans and animals. In the study, samples were collected from forty African catfish (Clarias gariepinus) harvested (n=10) from three selected polluted rivers (Eleyele, Oluyole, Dandaru Rivers) and a reference Fish farm (Fol-Hope Limited, Ibadan). Water samples were also collected from all the sites and analyzed for heavy metals. Based on previous findings, the water source of the reference fish farm was free from industrial discharge or contaminants that could cause pollution. Haematology, erythrocyte osmotic fragility test (OFT), heavy metal determination, in vivo micronucleus assay, and histopathology were determined.

The results showed significantly lower RBC, PCV, and Hb values (P<0.05)). In contrast, MCV and
MCH values increased in blood samples of catfish from the Oluyole and Eleyele Rivers relative to the reference Fish farm (Fol-Hope). Likewise, an increase in the erythrocyte osmotic fragility of the RBC was observed in blood samples of fish inhabiting the polluted water, coupled with a significant rise in the activities of AST, ALT, and ALP. However, fish from the Dandaru River had higher PCV, Hb, and RBC values than those from the reference Fish farm. Samples of water from the river sources and the liver and gills of fish samples there were observed to be contaminated with heavy metals such as Cd and Mn. Genotoxicity assay displayed a significantly higher frequency of micro-nucleated polychromatic erythrocytes (MnPCEs) in the fish collected from the polluted sites compared to the reference site. The histopathological lesions in the fish liver from the contaminated sites showed marked and severe disseminated congestion involving the vessels and sinusoids. The Kidney revealed severe distortion of the architecture, characterized by outright loss of tubular structure, desquamation, atresia, and degeneration.

In conclusion, the study revealed plausible fish health complications in fish inhabiting polluted streams with toxicities resulting in anaemia, liver damage, DNA damage, and possibly cancer. Thus, caution must be exercised when consuming fish from polluted rivers because they could be potentially harmful to humans thereby, constituting a public health risk.