Thiodon toxicity: non-specific phosphomonoesterases in nine freshwater teleosts.

The effect of various concentrations of thiodon on tissue non-specific phosphomonoesterases was studied in 9 edible freshwater teleosts from a tropical environment. Sublethal doses (5 and 10 ppm) of thiodon increased alkaline phosphatase in liver, muscle, kidney and brain, while lethal doses (15 and 20 ppm) decreased it. The reverse was the case with acid phosphatase. The greatest changes were recorded in kidney and liver. The increase in the activity of acid phosphatase after lethal doses might be attributable to rupture of the cellular and lysosomal membranes. The decrease in alkaline phosphatase activity might be related to the fall in pH following rupture of these membranes. The changes were greater in major carp species (C. catla, L. rohita and C. mrigala) than in catfish (H. fossilis, C. batrachus and M. seenghala) or snakehead species of murrels (C. striatus, C. punctarus and C. marulius).