Abstract: An acute toxic experiment of “Mie fei ling” on Nile tilapia (body weight: 34.65±5.69 g) was conducted to study the histopathology changes in gill, liver and kidney tissues and the mechanism of specific poison effect on Nile tilapia was explained. Results showed that the 24, 48, 72 and 96 hLC₅₀ values of “Mie fei ling” on Nile tilapia were 0.148, 0.103, 0.048 and 0.032 mg·L^-1, respectively. Necrosis, desquamation, fusion, shortening and curling of secondary lamellae, and secretion of mucous cells were observed in gill tissues after exposed to “Mie fei ling”. Hepatic lesions in the fish exposed to “Mie fei ling” were characterized by hypertrophy of hepatocytes, vacuolar degeneration, nuclear pycnosis, congestion and cloudy degeneration of hepatocyte. Tubular degenerations and congestion were observed in the kidney tissues of fish after the exposure. The degree of tissue damage by “Mie fei ling” was in order of gill>liver>kidney. Therefore, the main cause of death of Nile tilapia exposed to “Mie fei ling” was likely due to its harm on tissues.

Key words: gravel-mulched field, soil organic carbon, soil organic carbon stock, soil aggregate