Sobrevivência na larvicultura do lambari do rabo amarelo (astyanax altiparanae) durante testes de reversão sexual.

Abstract

The Yellow-tailed Lambari is attracting more and more attention from the market and fish farmers due to its excellent production performance, flavor, demand and market diversity, which encourages the search for new technologies and new techniques in its cultivation. An obstacle to the commercial production of this species is sexual dimorphism with its productive implications and the difficulty of applying sexual reversion techniques due to its demand for live food in the larviculture phase. In this work, the application of sexual reversion protocols and the survival of larvae subjected to hormone exposure were evaluated, based on direct and indirect tests and immersion bath, with inert food from the first moment of absorption of the yolk sac. 1000 animals were used per treatment, where they were divided into: G1 - Control Treatment; G2 - Direct Method 20mg of 17-β-estradiol (ET) /kg of feed; G3 - Direct Method 40mg of ET/kg of feed; G4 - Indirect Method 20mg of 17 α methyltestosterone (MT) /kg of feed; G5 - Immersion Bath 4mg of ET/liter of water; G6 - Immersion Bath 4mg of MT/liter of water, with immersion baths lasting 36 hours, and the direct and indirect methods lasting 30 days with six feedings per day with hormone in the feed. After a period of 60 days from the beginning of the experiment, the number of animals in each group was counted and subsequent relative survival percentage analysis was performed: RSR = (%survival in the supplemented group/% survival in the control group) x100. Obtaining the average percentage survival and relative survival results, respectively: G1: 37,5%; G2: 22,8% e 60,8%; G3: 26,8% e 71,5%; G4: 56,5 e 150,7%; G5: 0% e 0%; G6: 30% e 80%, subsequently subjected to the Chi-square test with the Bonferroni correction, which considered 6 groups and a P<0.008333.The results obtained were favorable regarding the survival of the animals, since the larva of the lambari has an initial need for live food and in this experiment only commercial feed was provided, which could be a promising step towards the successful application of sexual reversal techniques in lambari and the production of female monosex batches.