Abstract

The study was performed in order to try to provoke the gonadotropin wave and ovulation in Chalcarburnus chacoides using GnRH analogue, pituitary extract and dopamine antagonist. Different doses and injection protocols were applied using a combination of LRH-Aa, metoclopramide and carp pituitary extract. C. chalcoidesshow wide individual variation and much slower response to different hormonal stimulation. Saline (0.9% Nacl) injected fish were used as a control group and no ovulation occurred in this group. Based on the spawning ratio, fertilization rate and hatching rate, the combination of LRH-Aa 5 µg/kg, carp pituitary extraction 2.7 mg/kg and metoclopramide 2 mg/kg bw doses were found to be more efficient than carp pituitary (4 mg/kg). Following the above procedure it was possible to obtain 80 ± 2% ovulated females in laboratory condition. Fertilization rate was 83 ± 5% and hatching rate 90 ± 3% of fertilized eggs. The survival rate of larvae was 81%. No females ovulated in the treatment group receiving metoclopramide at 10 mg/kg and LRH-Aa alone at 100 μg/kg.

Key words: Chalcarburnus chalcoides, spawning, LRH-Aa, metoclopramide, carp pituitary extract.