Observation of embryonic and early larval development of striped gourami, Trichogaster fasciata (Perciformes: Osphronemidae)

Background: The striped gourami, Trichogaster fasciata, is depleted due to loss of habitat and overfishing. The striped gourami has virtually disappeared from the areas where it was abundant, such as rivers, canals, haor, baor and beels. T. fasciata is nutritive, economically and ecologically very valuable. It is vital to assess its early developmental biology for fry production and suitable rearing technique to repopulate this species in the freshwater bodies. Material and Methods: Brood T. fasciata was collected from local wild source. The brood T. fasciata was reared with polyunsaturated fatty acids supplemented diet for 3 months. T. fasciata was bred spontaneously. Fertilized eggs of T. fasciata were incubated in 2 mini circular bowl hatcheries (50 L capacity) with provision of continuous water supply and the embryonic and larval stages were recorded using a binocular microscope and a digital camera-equipped microscope. Results: The fertilized eggs were spherical, transparent, buoyant, non adhesives and brownish in colour, with an average diameter of 0.30-0.60 mm. First cleavage occurred within 25-30 min of postfertilization at 26±1°C. Hatching started at 22 h post-fertilization and completed within 24 h at the same temperature range. New hatchlings were 2.0-2.5 mm long devoid of mouth and pigmentation and started feeding within 48-60 h post-hatching. Depletion of the yolk-sac and development of the gills occurred on the second day of hatching. Conclusions: Therefore, the findings of the present study may help establishing the large scale seed production technique of T. fasciata.