Reprodução induzida da piabanha, Brycon insignis (Steindachner, 1876), mantida em cativeiro

Abstract

Studies of induced spawning of piabanha, Brycon insignis, were developed from January to February/96 and February/97, with 3 to 5 years old individuals maintained in captivity. The selected females presented swollen abdomen and red genital papilla, 60% of oocytes with eccentric germinal vesicle. Thirty-three females were induced to spawning through a single dose of 5 IU/g of hCG (human Chorionic Gonadotropin); 17 females received two application: 0.5 and 5 mg/kg of crude carp pituitary extract in an interval of 10 hours; 18 received one application of 0.5 mg/kg of crude carp pituitary extract and, after 10 hours, 5 IU/g of hCG; and 5 females received a single dose of 0.9% saline solution. About 10 hours after the last hormonal application, 43 females responded positively to the hormonal treatment releasing eggs by extrusion. The percent frequency distribution of the oocytes diameter in the initial sample presented unimodal tendency, with mode in 1250 μm. Considering the different hormones utilized, the most efficient was hCG in a single dose and the less efficient was the hormone of carp pituitary applicated in two doses. The males received one dose of 3 IU/g of hCG. The females released a mean of 24,690 eggs, wich after fertilization and hydration presented an sphere form, were demesal and non-adhesive, with mean diameter from 3785 to 3900 μm, and had an expressive perivitelin space and a hard chorion. The rate of fertilization ranged from 20 to 96% and that of hatching, from 0 to 85%. The water temperature was 26°C ± 1°C.