Invers?o sexual de larvas de betta Betta splendens por meio de manipula??o t?rmica

• Autor(a) principal: Fran?a, Igor de Fiuza
• Data de Publicação: 2020
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFRRJ
• Texto Completo: https://tede.ufrrj.br/jspui/handle/jspui/5883
• topic: Piscicultura; Ornamental; Masculiniza??o; Larvicultura; Fish-farming; Ornamental; Masculinization; Larviculture; Zootecnia

Regarding to Aquaculture, ornamental fish farming has grown exponentially in recent years in Brazil. Among the species reared, the betta, Betta splendens, has great commercial importance in Brazil and in the world, being easily kept in small containers. Among its characteristics, the males of the species have marked development of the fins and more vibrant colors, attributing singular beauty and adding superior value when compared to the females. The present experiment aimed to evaluate the influence of the temperature factor during Betta splendens larviculture, and its possible effects on mortality and proportion of males and females obtained, seeking to achieve a higher proportion of males through thermal manipulation, since they are of greater commercial interest. For this purpose, 20 couples were used to reproduce and breed the larvae used in the experiment. Subsequently, the newly hatched larvae were separated into groups of 30 animals with each group inserted in 40 beakers that represented the experimental units. These were subdivided into different thermal regimes, named: T25, T28, T30 and T33 (25, 28, 30 and 33 ?C, respectively). A randomized design followed (4x10). The thermal treatment was maintained until 15 DAH (days after hatching), at which time the temperature of 28 ?C was restored for all treatments. At the end of the thermal regime and again at 45 DAH, mortality was counted, aiming to assess the direct and residual effect, respectively, of the tested temperatures. At the end of the experiment, the number of males and females obtained in the different heat treatments was counted to analyze the sexual proportion obtained. All results were submitted to ANOVA (5%) and - in case of significant difference - the Tukey test at 5%. There was a significant effect of mortality as a function of temperature only at 15 DPE (P <0.001) where treatments T25, T28 and T30 showed the lowest values for this parameter compared to T33. For sex ratio, the treatments that showed the highest values for the proportion of males obtained (P = 0.037) were T28, T30 and T33 (45.74; 51.14 and 67.21%, respectively). It is concluded that the thermal manipulation during the larval period in Betta splendens can be a strategy to increase the proportion of males, and the increase in mortality due to temperature manipulation should be considered.