Morfologia espermática de Astyanax lacustris após a indução anestésica com óleos essenciais

Abstract

The reproductive management of fish involves selection, transport, handling, and hormonal induction, which are stressful procedures capable of affecting gamete quality. Essential oils have been studied as anesthetics to reduce this stress. However, few studies have evaluated the effects of these oils on the reproductive characteristics of Neotropical South American fish. The yellow-tail lambari (Astyanax lacustris) was used as a model to develop reproductive management protocols for Neotropical South American species. This study aimed to evaluate the sperm morphology of A. lacustris after anesthetic induction with essential oil. The experiment was conducted with 108 fish (14.38 g), distributed into three treatments: (i) control; (ii) basil essential oil; and (iii) eugenol. The fish were maintained in 20 L aquariums, with six fish per tank (replicates). After 220 degree-hours of hormonal induction with carp pituitary extract (2.5 mg kg⁻¹), the fish were anesthetized according to the established treatments for semen collection. For sperm morphology analysis, 10 µL of semen were placed in a 1.5 mL microtube containing 5% BTS®, 1,000 µL of buffered saline formalin (4.6%), and 10 µL of Bengal rose stain. Two 10 µL aliquots were placed on slides inclined at 45° and analyzed under a light microscope (40× magnification), counting 200 cells per slide. The number of normal spermatozoa did not differ significantly when fish were anesthetized with basil essential oil (119.75±24.85) and eugenol (122.33±28.73) compared to the control group (147.20±17.47). The main sperm abnormalities observed in anesthetized and non-anesthetized fish were broken tail, coiled tail, short tail, and detached head. It is concluded that the anesthetics used did not influence the sperm morphology of yellow-tail lambari (Astyanax lacustris).