Seasonal changes in liver and serum proteins, serum calcium, inorganic phosphate and magnesium levels in relation to vitellogenesis in a freshwater catfish, Heteropneustes fossilis (Bloch).

Female specimens of Heteropneustes fossilis show marked seasonal changes in liver and serum proteins, serum calcium, inorganic phosphate and magnesium levels in relation to the ovarian cycle. Their levels increase with the ovarian maturation, record the maximum values during the prespawning phase and gradually decline during spawning and postspawning phases. Thus, a positive correlation exists between liver and serum proteins, serum calcium, inorganic phosphate and magnesium levels during the annual ovarian cycle which seems to be related with vitellogenin synthesis.