Seasonal correlative changes between sex steroids and lipid levels in the freshwater female catfish, Heteropneustes fossilis (Bloch)

Circannual variation in plasma levels of testosterone (T), oestradiol-17β(E₂) and 17α-hydroxy-progesterone (17α-OHPg) were measured in female, Heteropneustes fossilis . T and E2 levels increased during the preparatory phase, reached their peak in the early prespawning phase and fell during the late prespawning phase to reach their lowest levels post-spawning. 17a-OHPg was detected from the late preparatory to the late spawning phase showing its peak during the early spawning phase. The levels of free fatty acids (FFA), monoglycerides (MG), diglycerides (DG), triglycerides (TG), phospholipids (PL), free cholesterol (CF)and esterified cholesterol (CE) were estimated in liver, plasma and ovaries. The preparatory phase showed hepatic lipogenic activity while during the prespawning phase TG lipolysis was increased by FFA. Ovarian CF was depleted by enhancing plasma E, levels during the prespawning phase. The gonadosomatic index reached its peak during spawning.