Rasbora daniconius commonly known as slender Rasbora is a lower risk threatened species in Assam. Though the population is not at risk presently but the natural population is showing a declining trend due to habitat loss as well as anthropogenic stress. The species is a potential ornamental fish. Therefore the present studies elucidates the embryonic and the larval development of Rasbora daniconius from fertilization to juvenile stage. The most important criteria for breeding programs are–in-vitro sexual dimorphism selection of brooders, male and female ratio for breeding. In males colouration is bright and the lateral band is prominent whereas the females are fainter. The ratio of male to female is 1:1 or 2:1. The fish is bred by striping and artificially fertilized. The fertilized eggs are spherical, semi adhesive and the diameter of egg proper ranges between 0.8–1.0 mm × 0.96 mm. First sign of cleavage is observed at 20m from hatching, the appearance of germ plug commences th

Embryonic, larval, Rasbora daniconius, in-vitro sexual dimorphism, organogenesis.

R. daniconius can easily be reared, matured and bred in aquarium condition. The study reveals precisely the time taken for the development of key stages of the species. It will further help in comparing the variation in organogenesis of related species of Assam. The larval and fry development will help in the replenishment of this species in natural environment and also help to improve the captive culture of the test species.

Paul, S. and Sarmah, S.K. (2019). Study of Embryonic and Larval Development of Rasbora daniconius. Biological Forum-An International Journal, 11(2): 72-76.