STAGES OF EMBRYONIC DEVELOPMENT OF THE "MATRINXí" Brycon cephalus (PISCES, CHARACIDAE)

Abstract

The "matrinxã†is an indigenous species from the Amazon Basin (Brazil). The development of oocytes is of the synchronic type, i.e., a large number of ovules are released at the same time. The egg development is characterized by a short embryonic differentiation and a larval period (26 ± 2.0°C). Metamorphosis ends practically 36 hours after fertilization and individuals reach fingerling stage with a structure similar to that of the adult, 48 hours after fertilization. The larvae hatch approximately 10-11 hours after fertilization, displaying slightly pigmented body, well evidenced eyes, traces of a digestive system, and first swimming movements. At the end of the first day of life, intense cannibalism is observed. Malformation of embryos is also observed in some individuals.