Effect of salinity on serum steroid levels and gonad development in common carp (Cyprinus carpio Linnaeus, 1758) reared in inland saline water

Abstract

The effect of salinity on serum steroid levels and gonadal development were investigated in the common carp Cyprinus carpio Linnaeus, 1758. Fishes were stocked in eight rectangular earthen ponds at four different salinities of 0, 5, 10 and 15 ppt. Changes in serum concentration of cortisol, 17 β – Estradiol, progesterone; 17α, 20β dihydroxyprogesterone and androgens were investigated. Gonadal histology in male and female C. carpio was studied at different stages of gonadal maturity till ovulation or spermiation. Serum steroid analysis showed significantly high levels (p<0.05) in fish groups reared at 0 and 5 ppt compared to 10 and 15 ppt. Significantly higher cortisol levels were found during ovulation or spermiation at 10 and 15ppt. In the present study, C. carpio was found to mature faster at 5 ppt as compared to higher salinities of 10 and 15 ppt, in inland saline water. Keywords: Aquaculture, Cyprinus carpio, Maturation, Salinity, Steroid hormones