The use of the urogenital papillae of male feral African sharptooth catfish (Clarias gariepinus) as indicator of exposure to estrogenic chemicals in two polluted dams in an urban nature reserve, Gauteng, South Africa.

The African sharptooth catfish (Clarias gariepinus) is indigenous to South Africa where it is commonly found in calm waters such as lakes, streams, rivers, swamps and floodplains. The males of this gonochoristic species can be readily distinguished from females via a distinct elongated urogenital papilla with a pointed tip, located just behind the anus. This structure is an androgen controlled secondary sexual characteristic and could potentially be affected by chemicals displaying endocrine disrupting properties during development.

The lack of endocrine disrupting effects in catfish (Clarias gariepinus) from a DDT sprayed area.

The exposure and response of the catfish, Clarias gariepinus, was studied in male specimens collected in the vicinity of a DDT spraying programme to control malaria. Two sites were situated in the DDT sprayed areas and one site upstream from exposed areas, used as a reference site. The collected specimens were analysed for DDT bioaccumulation and the extent of associated effects.