The present investigation has been conducted to study of the effect of acute exposure of sublethal doses of arsenic tri-oxide (As(2)O(3)) on blood glucose level in an Indian teleost, Clarias batrachus, during their post-breeding season (October to January). The effect was correlated with the sex and doses used with time. Acute exposure of As(2)O(3) of 5, 10 and 15 mg/l for six consecutive days (i.e., 144 h) has been conducted on both sexes of C. batrachus. During the present investigation, it was noticed that the females were more reactive to arsenic in producing hyperglycemia compared to their male counterparts. The difference between males and females to produce hyperglycemia on exposure to arsenic appears to be dose dependent, as lower doses of 5 and 10 mg/l exhibit less difference between the two sexes compared to the highest dose order of 15 mg/l. After 96 h of treatment, a normoglycemic condition was observed in both sexes. However, no significant differences in average normal blood glucose levels were noticed in male and female C. batrachus during the post-breeding season.