Fish histopathology as a tool to assess the health status of freshwater fish species in the Albasini Dam, Limpopo Province, South Africa

MSc. (Zoology)The Albasini Dam was used as a reference site outside the DDT (1, 1, 1-trichloro-2, 2-bis (p-chlorophenyl) ethane) - sprayed area in a previous survey conducted from 2006 to 2008. DDT, endocrine disrupting chemicals and inorganic chemicals were detected in the dam. A histological analysis of fish from the dam showed histological alterations in heart, liver, gills, and gonads. Therefore, it was necessary to follow up the health status of the dam by monitoring the levels of organic and inorganic chemicals and their effects on fish. The aim of the present study was to determine the health status of three freshwater fish species, Clarias gariepinus, Oreochromis mossambicus, and Coptodon (Tilapia) rendalli from the Albasini Dam, using fish histology as a biomonitoring tool. In total, 18 fish were sampled using gill nets; these included Clarias gariepinus (n=5); Coptodon (Tilapia) rendalli (n=4) and Oreochromis mossambicus (n=9). The histology-based fish health assessment included a standard fish necropsy; a calculation of blood parameters (haematocrit, leukocrit and total plasma protein); somatic indices and the condition factor and a qualitative and semi-quantitative histological assessment of five target organs: liver, heart, gills, kidney and gonads. Water, sediment and fish muscles samples were collected and analysed for inorganic chemicals and organic chemicals. Inorganic chemicals were analysed by means of Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) and Inductively Coupled Plasma-Optic Emission Spectrometry (ICP-OES). Organic chemicals in water and fish muscles were analysed using Gas Chromatography-Mass Spectrometry (GC-MS). Nutrients and physical parameters of water were also measured..