Ontogeny process comprises the embryo development from the moment of fecundation, through embryonic development phase, until hatching or later phases. The study of embryogenesis is an important tool for growth study of the species within their natural environment. The present work observed and registered the main stages of Betta splendens embryonic development, one of the most promising ornamental species mostly because of the increasing commercial interest, to describe the initial ontogeny and thus contribute for a better understanding about the biology of this species. It was possible to observe that as the embryonic time passes, there was a decrease in yolk height and then at its length, mainly at the final phases of embryonic period. Newly hatched larvae did not use feed from exogenous source. The embryo of B. splendens presented embryonic development phases similar to the observed for other teleostei species. The 1st cell division/blastula was observed at 1 HPF (Hour-Post-Fertilization) until the 7.5 HPF; the gastrula period was observed starting at 8.5 HPF until 14.5 HPF; the organogenesis period was from 15 HPF until the hatching moment, at 38 HPF.
embryo; ornamental; siamese fighting-fish; yolk