Year-round sexual maturation of bighead carp Aristichthys nobilis (Richardson) reared in floating cages in Laguna de Bay (Philippines).

Abstract

Sexual maturation in bighead carp Aristichthys nobilis reared without supplemental feeding in floating cages in Laguna de Bay was observed year-round. Percent maturation ranged from 3 to 94% in females and 0 to 82% in males from July 1985 to July 1986. High maturation rates in both sexes occurring in March 1986 were positively correlated with high inorganic turbidity in the lake. Low natural food productivity (phyto- and zooplankton) during high turbidity did not negatively affect fish growth. Fish may have depended partly on suspended particles as additional food sources when production of more suitable food (zooplankton) was low. Increased production of natural food as a result of water clearing by seawater intrusion during May to September did not enhance growth and maturation of the fish. There was a low negative correlation between chlorinity and percent maturation of both sexes.