Spawining induction with natural and artificial fertilization and egg incubation of the fat snook (Centropomus parallelus)

Abstract

The artificial propagation of the wild fat snook, Centropomus parallelus, was investigated in laboratory. This study tested a protocol for spawning induction using human Chorionic Gonadotropin (hCG) and an incubation system with different egg densities. Females were injected with 1,100 IU of hCG/Kg, and males with 500 IU/Kg. Fish were held in tanks of 160L capacity, with two males and one female. Temperature was 23,9-27,3ºC and salinity was 35. A total of 19 hormonal inductions were carried out, resulting in 7 natural spawnings and 12 with artificial fertilization. The best fertilization and hatching rates were obtained when ovulation occurred at 32-36 h post-induction (816-972 hour-degrees). The average relative fecundity was 373.000 eggs/Kg of body weight. Viable larvae were obtained in 43% of the natural spawning trials, and in 58% of the artificial spawning trials. In the incubation system, density was 553 to 1,705 eggs/L, using 9 incubators with 37L capacity inside a 2,000-L tank. Eggs were maintained in an open flow-through system with continuous aeration. After 19 hours, the number of hatched larvae was 305 to 850/L. Spearman test showed no correlation between egg density and hatched larvae (P>0.05). The average hatching rate was 52%.