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Evaluation of toxicity and response of African catfish (Clarias gariepinus) exposed to manganese chloride solution

This study investigated the acute toxicity and behavioural response of African catfish (Clarias gariepinus) to manganese chloride (MnCl ) solution.  One hundred (100) pieces of juvenile Clarias gariepinus were acclimatized 2 for 14 days in ten (10) plastic bowls containing 25 L of water each. The acute-toxicity of manganese chloride, LC and sub chronic exposure (28 days) were investigated. For sub-lethal exposure; fifty pieces of C. gariepinus  50 were divided into five groups of ten in bowls labelled (A to E). The fish in groups (A to D) were exposed to manganese chloride solutions at: 68.5, 137, 205.5 and 274 mg/L respectively while group G served as the control. On day 28, the exposed fish were sacrificed; blood, muscle, liver, and gills were collected for haematological and histological studies. The activities of the superoxide dismutase (SOD) and glutathione-Stransferase (GST) were determined using standard methods. The manganese concentrations in the liver, gills and muscle tissues were determined using Atomic Absorption Spectrophotometer (AAS). The LC obtained 50 was 2.74 g/L. The mean water temperature showed that there was no significant variation at (p gill > muscle. The histopathological study revealed alterations in the liver, gill and muscle tissues. This study concluded that manganese at concentration greater than 137 mg/L elicits adverse effect on C. gariepinus growth performance, haematology, histopathology as well as liver SOD and GST activities. 
Key words: Behavioural response, Cat-fish, Juvenile, Manganese chloride, Toxicity