An Empirical Analysis on the Breeding and Feeding Behaviour of Estuarine Rice Fish Oryzias melastigma (McClelland, 1839)

The breeding and growth characteristics of Oryzias melastigma were investigated under controlled laboratory conditions to assess its suitability for aquaculture. The species exhibited a short-generation time of 2 to 3 months that thriving in artificial-seawater at 28°C with a 14-hour light/10-hour dark-cycle. Sexual-dimorphism became apparent after one-month; with males developing a prominent anal-fin, aiding sex identification for experimental-populations. Feeding-experiments revealed that Oryzias melastigma, preferentially consumed early instar mosquito-larvae, showing high feeding-efficiency, particularly on smaller-prey. Additionally, the species demonstrated increased reproductive-success when supplemented with Ulothrix, suggesting its effectiveness as a feed to enhance egg-production and hatchling-survival. The sensitivity of eggs and larvae to pollutants like ammonia and CO2 indicates the species' potential as a bio-indicator for water-quality. Statistical analysis of reproductive-output indicated that a mature-female, could produce over 1.5 million eggs annually; contributing to aquaculture-systems as a food-source for carnivorous-species. This potential-biomass, when applied to fish farming, could significantly enhance the production of species like Lates calcarifer. The study highlights breeding and feeding behaviour of estuarine rice fish, Oryzias melastigma.