Modulation of Testicular Functions by 4-Nonylphenol in Catfish Heteropneustes fossilis and Clarias batrachus

The present study compares the effect of the same dose of 4-NP on both the physiologically different male catfishes concerning their reproductive function. Nonylphenol (4-NP) is a persistent organic water pollutant that disturbs many physiological processes in aquatic species. It is extensively used as industrial organic compounds and as a biodegradation byproduct of alkylphenol ethoxylates which are a form of industrial effluents and released in water bodies. This experiment was taken up to compare the effects of 4- NP on the two indigenous male catfish Heteropneustes fossilis and Clarias batrachus. Effects of 4-NP (low dose: 64μg.L-1 and high dose: 160 μg.L-1) on the behaviour, gonadosomatic index (GSI), structure, and function of testis of both fish were analyzed. Fishes were exposed during the preparatory to pre-spawning phase for 30, 45, and 60 days. There was a significant dose- and duration- dependent decrease in the GSI. Histopathological alterations were observed in the testes of both along with altered steroid biosynthesis. There was a dose and duration-dependent decrease in the level of testosterone. Estradiol 17β(E2) level was significantly increased at a low dose for 30 days but significantly decreased at 45 and 60 days. E2 level was significantly decreased at a high dose for all durations in testes of H. fossilis and C. batrachus. Even though the catfishes investigated were physiologically different their response toward the 4-NP toxicity was not significantly different. Thus, we can conclude that 4-NP affects the structure and function of testes as well as steroid hormone levels in both catfish species. There is an intense need for awareness and concern about such pollutants to prevent the threat it poses to the aquatic species and maintain balance in the aquatic ecosystem.