Observations on the reproductive performance of three mouth-brooding tilapia species in low-salinity underground water

摘要

The reproductive performance and seed production of three mouth-brooding tilapia species, Oreochromis spilurus (Gunther), Oreochromis aureus (Steindachner) and Taiwanese red tilapia hybrid, were compared in low-salinity underground water (3-5 g L-1) to select species with the highest reproductive rate. Two-year-old males and females having average body weights of 454 and 259 g, respectively, were stocked in 2-m(3) fibreglass breeding tanks (two tanks per species) at 1:3 male to female sex ratio and at average density of three fish m(-2). Seeds (unhatched eggs; yolk-sac fry and the swim-up fry) were collected weekly for 112 days. The results showed O. spilurus to have significantly higher (P<0.05) mean spawning parameters expressed as total seed tank(-1) (84 154), seed kg female(-1) day(-1) (284), seed m(-2) day(-1) (190.3) and seed female(-1) day(-1) (76.3), than O. aureus and red tilapia. Monthly seed production in O. spilurus and red tilapia gradually increased from May, peaked in July and declined in August, while in O. aureus, it continued to decrease from May to August. In this study, the observed production levels of seed in O. spilurus were among the highest levels reported for tilapia; therefore, O. spilurus could be selected as a potential candidate for mass seed production in commercial tilapia hatcheries.