Cold, heat, or double thermal shock in tambaqui (Colossoma macropomum): triploid induction, fertilization rate, growth, and hematological variables

ABSTRACT This study assessed the effectiveness of triploidy in tambaqui (Colossoma macropomum) and compared the fertilization, survival, growth performance, and hematological parameters of diploid and triploid fish. After artificial reproduction, freshly fertilized eggs were subjected to cold, heat or double thermal shock or were not exposed to the thermal shock (control group). Double thermal shock presented fertilization rate significantly lower than other treatments. Larvae submitted to cold thermal shock had a higher weight than the control and heat thermal shock treatments. The final weight of juveniles exposed to cold thermal shock was significantly higher than the other treatments with triploid induction. There was no significant difference for survival and hematological variables. The cold thermal shock produced more triploid individuals (33.33%) than the heat and double thermal shock (both 11.11%). The cold thermal shock was the most effective technique for obtaining triploid fish and it contributed to increasing the weight of tambaqui larvae.