Reproductive biology of sagor catfish (Hexanematichthys sagor Hamilton, 1822) in Can Gio water, Vietnam

Sagor catfish (Hexanematichthys sagor Hamilton, 1822) is one of the most popular fish caught in Can Gio reserve biosphere. A study on reproductive biology was conducted to evaluate the reproductive parameters, including male-female distinction, gonadal development stages, sex ratio, spawning season, fecundity, and size at first sexual maturity. The results showed that the number of males and females in the nature was not significantly different. Male and female fish can be distinguished when they reach the mature size. Gonadal of the fish pass through five stages of maturation. The histological screening of gonad, percentage of maturation stage and gonadal somatic index value of the fish showed all year round spawning with a peak of spawning female from March to August. The length at first sexual maturity of the fish is 25.39 cm. Fecundity ranged from 60 to 145 ovaries/individuals strongly related to weight and length. The current findings provide the scientific foundation for the purpose of fishery resource management and artificial breeding of the blue sagor catfish.