Annual changes in the total Gonadotrophic potency in relation to Gonadal activity in the freshwater catfish,Clarias Batrachus(L.)

The gonadotrophic potency in pituitary and serum of both sexes of C. batrachus was evaluated by measuring stimulated ovarian 32P uptake in hypophysectomized H. fossilis in response to the injections of pituitary extract and serum of C. batrachus. Gonadal activity was assessed by GSI, gonadal 32P uptake and gonadal lipid and cholesterol levels. Pituitary and serum gonadotrophic potency in C. batrachus increased along with GSI, gonadal 32P uptake and gonadal lipid and cholesterol contents during the breeding season. The above period was marked with increasing photoperiod and temperature. Concentrations of lipid and cholesterol in the ovary also exhibited the similar pattern, but testicular lipid and cholesterol concentrations were low during the above period. These parameters showed the reverse trend during the non‐breeding season, when the photoperiod was short and temperature was low.