Seasonal variation of giant gourami (Osphronemus goramy) spawning activity and egg production in aquaculture ponds

Abstract

The giant gourami Osphronemus goramy Lacépède, 1801, spontaneously spawns in captivity, making nests for egg deposition when suitable nest supports and nesting material are made available in rearing facilities. The seasonal variation in reproductive performance of the giant gourami was characterized during a 20-month experiment in two compartmentalized ponds (about 550 m2 each) at a fry production center in West Java, Indonesia. A total of 208 giant gourami broodfish were introduced in the two experimental ponds, with a sex-ratio of one male to three females in each of the 52 spawning compartments delimited by vertical nets. Nesting supports in each spawning compartment were examined every two days for the presence of eggs resulting from natural reproduction. Three performance indicators were quantified from the collected nests: spawning frequency (monthly number of spawns per female), effective fecundity (number of eggs per spawn) and egg quality (estimated from the proportion of clear living eggs in each spawn). The seasonality of giant gourami reproduction was analyzed as a function of seasonal variation in rainfall, rearing water temperature and day length. Based on a total of 413 collected spawns, the multiple linear regression models did not show any significant relationship between giant gourami spawning frequency and the three environmental variables studied. In contrast, the number of eggs per spawn was highly and positively related to rainfall (p < .0001), moderately and negatively related to water temperature (p < .001), and weaklier and negatively related to day length (p < .01). The proportion of clear eggs was positively related to day length (p < .01). Overall, this study represents one of the first comprehensive datasets on the reproductive phenology of giant gourami, and as such will be helpful in formulating broodfish management strategies for the species.