Seasonal fluctuations in plasma sex steroid hormones of Indian major carps: Mrigal (Cirrhinus mrigala), Catla (Labeo catla) and Rohu (Labeo rohita)

The present study was conducted in 2012 to evaluate the seasonal fluctuations of plasma sex steroid hormones including testosterone (T), 17β-estradiol (E2) and progesterone (P) in Indian major carp brooders in Khuzestan Province, Iran. The results revealed that T levels in females of Labeo catla and Lobeo rohita did not change during a year; however, females of Cirrhinus mrigala had the highest plasma T level (0.57±0.16ng mL-1) during maturing stage in spring compared to the other seasons. In males, bimodal peaks of plasma T was noticed in L. catla (summer and winter) and L. rohita (spring and winter), but in C. mrigala the highest T level (0.19±0.04ng mL-1) was observed in winter. Plasma E2 levels surged during autumn and winter in females of C. mrigala. The lowest level of plasma E2 was noticed in summer in females of L. rohita, but it did not affect in males. The highest level in female brooders of L. catla and C. mrigala was noticed in winter and spring, respectively; whereas, in female brooders of L. rohita, the highest (0.86±0.1ng mL-1) and the lowest (0.16±0.04ng mL-1) plasma P levels were observed in autumn and summer, respectively. These results indicating high temperatures in Khuzestan Province could be truncated reproductive development in Indian carps.