EFEITO DA TRIPLOIDIZAÇÃO COM DIFERENTES TEMPERATURAS SOBRE A SOBREVIVÊNCIA E DESEMPENHO DO TAMBAQUI NA FASE LARVAL

This study evaluated double thermal shock to induce triploidia in tambaqui
(Colossoma macropomum) and compares (survival and growth) variables of diploid
and triploid fish. After artificial reproduction, newly fertilized oocytes were subjected to hot (40°C) and (42°C) thermal shocks for two minutes and then to cold shock (4°C) for 25 minutes. Intact oocytes were used as controls. Biometrics were done to evaluate the reproductive parameters (fertilization and survival rate) and performance (mean initial weight - PI) and (initial mean length - CI). The level of ploidy was confirmed by flow cytometry. Data were submitted to the normality test of Shapiro - wilk and ANOVA, differences were considered significant when (p <0.05). The rate of fertilization and survival was reduced in the groups treated with temperature (p <0.05). Weight (PI) and Mean (CI) larval growth presented better performances in the 42°C (triploid) group than in the 40°C and Control group. The results indicated that the heat treatment at 42°C induced triploidization of the tambaqui, obtaining superior zootechnical performance in relation to the condition at 40°C and without any heat treatment.