The induction of spawning behaviour in Puntius gonionotus (Bleeker) by treatment with prostaglandin PGF2α

Groups of Puntius gonionotus were brought into breeding condition by treatment with extracts of homoplastic pituitary material. Spawning in P. gonionotus includes a number of distinctive features which appear to be adaptations to reproduction in a riverine habitat. These features include the absence of a specific substrate requirement, the production of non-adhesive, buoyant eggs, an elaborate circling display by the male, and a long spawning run during which gametes are dispersed across the current. Spawning activity began 3–4 h after treatment with pituitary material. The relatively sudden increase in female responsiveness and attractiveness to males appears to coincide with the occurrence of ovulation. It is hypothesized that at this time the female releases a chemical signal which attracts and excites the male. Females participate in a number of spawning runs over a period of 30 min, thereafter female activity decreases rapidly. Injections of a prostaglandin (PGF2a) were effective in inducing spawning activity in non-gravid females. This finding provides support for the hypothesis, based on work with goldfish, Carassius auratus, that prostaglandin provides a link between periovulatory events in the ovary and the brain mechanism governing spawning activity.