Abstract

This work reports the seasonal change and variation in the physico-chemical properties of the water in Osinmo reservoir in Southwestern Nigeria and the effects on tissue distribution of the metabolic enzymes, arginase and rhodanese are the two fish species (Clarias gariepinus and Heterotis niloticus) collected from the reservoir. This study was carried out to correlate the activities of the enzymes with metabolic status of the fishes and physico-chemical properties of the water. The enzyme activities varied significantly in the different tissues of the C. gariepinus. The liver showed the highest mean value of activity and the intestine had the least mean value. In the H. niloticus, they showed the highest mean value of activity while the bile showed the lowest mean value. The activities of the two enzymes in the water reservoir were determined at regular intervals over a period of ten months in 2011, spanning both dry and rainy seasons. The activities of the enzymes varied significantly through the two seasons. Arginase was at its peak in June while rhodanese was at its peak in September. The distribution of urea in the reservoir varied significantly in the period studied; the highest mean value was in July while the lowest was in February.

Key words: Water properties, urea; cyanide, enzymes, tissue distribution.