A total of 362 specimens of the fish Synodontis clarias were randomly selected and subjected to parasitological examination for helminth parasites. They were collected over a period of one year from Lekki lagoon, Lagos, Nigeria. The prevalence of gastrointestinal infection was 38.7%. The helminth worms found include two cestodes, Proteocephalus spp., Wenyonia acuminata, and a nematode species, Raphidascaroides. Male specimens (196) presented a higher rate of infection (37.8%) than female specimens (166) which showed a rate of 23.5%. The overall worm burden was high (678) and it was independent of fish sex and fish size. Rev.

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Highlights Occurrence of parasites in fish could bio accumulate heavy metals by as much as 200 % more than values present in fish tissues. Parasitic infection in fish is positively skewed towards male fish. Parasitism in fish alters histological structures of vital fish organs. Combined effects of parasitism and heavy metal pollution in fish elicits antioxidant response in fish.

Polychlorinated biphenyls (PCBs) are a class of non-polar toxic chemical compounds consisting of 209 congeners of which only about 130 have been identified in commercial products (Berg et al., 2017). PCBs are used in industrial applications such as hydraulic fluids, lubricants, inks, plasticizers, agrochemicals, etc. from which they leak into soil, surface and underground water (Cappelletti et al., 2015). Discharge of industrial waste into water bodies, and incineration are predominant sources of PCBs in Nigeria (Wang, 2002; Okoh, 2015). Waste management in Epe, Nigeria include land filling, dumping site, and open incineration. These methods are liable to contaminate underground and surface water bodies, thereby gaining access to the aquatic food chain where they are biomagnified up the ARTICLE INFO