Mudskipper Periophthalmodon septemradiatus is a euryhaline and an amphibian species, both aquatic and terrestrial habitats. It is widely distributed in the mangrove swamps and muddy areas in the Asian regions. This study was conducted to provide basic information on the morphology of embryonic and larvae and describe the environmental parameters of this species in the lowland area of the Mekong River Basin for artificial reproduction, management, and conservation implication. The study was conducted from November to December 2020. Eggs of P. septemradiatus were collected from the natural habitat, a burrow in the small tributaries of the Mekong River in Binh Thuy District, Can Tho City, located in the Mekong Delta, and incubated under hatchery conditions. The results showed that the fertilized
eggs have an elliptical shape with one adhesive side. The fish larvae are more active inside the eggshell before hatching. The eggshell is broken, and hatching occurs. The newly hatched larva has a mouth and eyes, but they are not completely developed yet. The eyes develop completely between 24 and 30 hours after hatching, and the mouth becomes fully developed between 5 and 7 days after hatching (DAH), at which time oil globules in the yolk sac are very small or disappear. After approximately 7–8 DAH, the fish larvae use up the yolk sac. The results of this study indicated that eggs and larvae of P. septemradiatus can develop in freshwater. This information can be useful in studies on artificial reproduction.

Keywords: Mudskipper, Periophthalmodon septemradiatus, fry, morphology.