Early developmental stages of Amazonian pacu Prosomyleus rhomboidalis derived from in loco reproduction

The objective of this study was to characterize macroscopically the female gametes, evaluate the survival rates, as well as describe in detail the embryonic development of Prosomyleus rhomboidalis . Three adult females from the Xingu River, presenting promptly ovulation were fertilized by the dry method using sperm from adult males. Egg incubation was set at 27.5°C, and oocyte characteristics and the main developmental stages were described. The results showed that the non-hydrated oocyte has an average diameter of 2.12 mm, yellow colour, spherical shape, is non-adhesive and the diameter increased after hydration at 0.36 mm, referring to the perivitelline space(PS). The fertilization rates (96.79 ± 9.52%) and hatching of normal larvae (96.21 ± 2.40%) were analysed, with hatching above 96%. After hydration of the eggs the PS arose and formed a visible animal pole ending with the hatching of the larvae 69 h and 39 min after fertilization. The description of developmental stages following fertilization was described for the first time in this species. The information presented in this work will serve as a basic support for new possibilities in conservation strategies, re-stocking and genebanking.