Description of the initial ontogenic development of the Dorada Brycon moorei (Characiformes: Bryconidae)

Ontogeny is a biological process associated with the appearance or disappearance of anatomical structures and physiological associated process. The objective of this work is to describe ontogenic development of Brycon moorei, an oviparous and potamodromous fish species. It is a contribution to a better understanding of its initial development. Samples were obtained from parents kept in captivity. Woynarovich-type incubators were used for the embryos and cement ponds for the larvae, both with a constant supply of water at an average temperature of 27 ºC and food availability. The hours post-fertilization (HPF) of ontogeny were recorded. The optic capsule was evident at 9 HPF, the opening of the mouth and anus at 23 and 24 HPF respectively. Duration of each phase during the embryonic period: cleavage (4 h), gastrulation (3 h), embryogenesis (7 h) and, of the larval period: vitelline larva (28 h), pre-flexion (61 h), flexion (80 h) and post-flexion (>170 h). In each period and phase the analysis of its shape was carried out using distance measurements. Larvae had a considerable increase in length with the HPF. Total number of myomers was kept constant since preflexion phase. Our results can be used to explain the general picture of early development of B. moorei under captivity conditions. Also, they can help develop better breeding methods for larvae in production and to find diagnostic characters that can be used at thein taxonomic level.