Histopathological changes in liver and thyroid of the teleost fish, Channa punctatus (Bloch), in response to ammonium sulfate fertilizer treatment.

In Channa punctatus exposed to safe (100 ppm) and sublethal (500 ppm) concentrations of the commonly used fertilizer ammonium sulfate for 6 months, from January to June, hepatocytes revealed initial hypertrophy followed by exhaustion as evidenced by degranulation, nuclear pyknosis, and focal necrosis. Thyroid follicles exhibited various degrees of hypertrophy, hyperplasia, hyperemia, and reduction in colloid content. Both in the liver and in the thyroid, changes were more pronounced in the 500-ppm-treated fish. These results suggest that this fertilizer, which is washed into the water system in small quantities, may cause dose-dependent dysfunction of liver and thyroid.