Validation of synthetic aromatase inhibitors for tilapia masculinization Oreochromis niloticus

Abstract

Tilapias are one of the main fish species for aquaculture worldwide; however their precocious reproductive behavior negatively affects growth and prompts culture unit overpopulation. To prevent this situation, a viable option is to use 100% male stocks for aquaculture purposes; thus hormone dietary supplementation is one of the most commonly used procedures for tilapia masculinization. A new line of research involves aromatase inhibitors as alternative to steroid hormones, with certain evidence of relative success achieving sex reversion in tilapia. In this study we validated the efficiency of two synthetic aromatase inhibitors during sex differentiation stage on tilapia fry fed for 28 days with diets supplemented with 17α-methyltestosterone 60 mg/kg (positive control), letrozole at 50, 100 and 200 mg/kg, exemestane at 1000, 1500 and 2000 mg/kg and a negative control group (hormone free) in three experiment. Survival, growth and final sex ratio were evaluated for each experiment. Male percentage showed significant differences among negative control and all treatments, achieving 100% masculinization for all groups. No negative effect was observed on survival (above 85%) and final individual weight in most cases. We conclude that synthetic aromatase inhibitors administration is an efficient method to produce 100% male tilapia populations.