Effectiveness of estradiol valerate on sex reversion in Astyanax altiparanae (Characiformes, Characidae)

Abstract

The objective of this study was to evaluate the effectiveness of estradiol valerate in an attempt to feminize the male Astyanax altiparanae. One thousand newly-hatched larvae were randomly distributed in four incubators. During a period of 30 days, estradiol valerate was administered in different dosages (20, 40, and 80 mg/kg of diet); the control group did not receive hormone in the diet. After 161 days of hatching, biometry was performed on 50 fishes per treatment group, and the gonads were analyzed. The hormone treatments were effective in feminizing A. altiparanae, achieving 70-76% of the desired sex, while the control treatment had 44% females. The hormone did not affect the growth of fish

Reproductive performance of lambari ( Astyanax altiparanae ) in a seminatural system using different protocols

“…In this experiment, a single dose (positive control and sGnRHa treatments) or a single injection with saline solution (Control) was applied. We defined 6 mg of CPE/kg in a single dose as the positive control because it is the most widely used hormonal induction protocol for this species (de Bem et al., 2012; Felizardo et al., 2012; Lira et al., 2018; Nascimento et al., 2017; Sato et al., 2006). Fish in the negative control were handled as in the other treatments, and the vehicle (0.9% saline solution) was applied.…”

“…The same changes occur in its natural reproductive behaviour, and it is sometimes classified as a migratory species (Harvey & Caroslfeld, 2003) or a species that just performs short‐distance lateral migrations (Suzuki et al., 2005). The reproduction of this species in captivity is obtained with (de Bem et al., 2012; Felizardo et al., 2012; Lira et al., 2018; Nascimento et al., 2017; Porto‐Foresti et al., 2018; Sato et al., 2006) or without hormonal induction (Chehade et al., 2015). The hypophysation is the most widely used method and one of the main controversial points concerns the number of doses, since lambari is reported to be induced by single (de Bem et al., 2012; Felizardo et al., 2012; Lira et al., 2018; Nascimento et al., 2017; Sato et al., 2006) or fractioned carp pituitary extract (CPE) doses (Porto‐Foresti et al., 2018).…”

“…Because lambari is considered a good biological model (small size and attainment of sexual maturity at approximately 4 months in captivity), some studies used traditional spawning induction protocols to obtain fries for sexual reversion (de Bem et al., 2012) and triploid assays (Nascimento et al., 2017), but without reproductive performance evaluation. No studies established an improved induced‐spawning protocol to supply the productive sector demand.…”

Effect of dosage of orally administered 17α-methyltestosterone on sex reversion of the yellowtail tetra Astyanax lacustris (Lütken, 1875)

“…At three dph, ad libitum feeding was initiated with a diet containing 55% crude protein (CP) supplemented with different doses of MT (0, 20, 40, and 60 mg 17α-methyltestosterone/kg feed) for 30 days, the same period tested before for direct hormonal sex reversal with estradiol-17β (Bem et al, 2012). Fish were fed five times a day.…”

“…The heterogeneity in the harvest size of adult males and females is a major problem faced by farmers. In order to decrease this variability and increase the efficiency and profitability of the cultivation of this species, the use of all-female progeny resulted in a higher growth rate when compared to traditional culture (Navarro et al, 2006;Bem et al, 2012). All-female progeny can be obtained via hormone sex reversal technique in a direct or indirect way, administering hormones by immersion or in the diet during the period of histological sexual differentiation.…”