Embryonic Developmental Response of Nile Tilapia (Oreochromis niloticus) to Different Aquatic Incubation Media

This study examined the comparative effects of pond water and rice field water on the embryonic development and larval viability of Nile tilapia (Oreochromis niloticus). A total of 300 fertilized eggs were incubated under controlled laboratory conditions using two distinct water sources, each replicated three times. Embryonic development was observed microscopically at 30-minute intervals, with documentation of cleavage, blastula, gastrula, organogenesis, and hatching stages. The results showed that embryos incubated in rice field water experienced significant developmental delays, irregular morphogenesis, and lower hatching rates (73.2%) compared to those in pond water (98.7%). Larvae from the rice field water group exhibited reduced motility, abnormal morphology, and higher post-hatching mortality. These adverse effects were attributed to physicochemical stress factors such as reduced dissolved oxygen, pH fluctuation, and potential agrochemical contaminants in rice field water. The study underscores the importance of water quality management in hatchery operations and recommends pretreatment or quality assessment of rice field water prior to use in aquaculture, especially in integrated farming systems.