EFFICACY OF SUPPLEMENTARY METHYLTESTOSTERONE AND ALOE VERA (L.) GEL MEALS ON MASCULINIZATION, GROWTH PERFORMANCE AND GONADAL DEVELOPMENT IN NILE TILAPIA, OREOCHROMIS NILOTICUS (Linnaeus, 1758)

Abstract

Uncontrolled reproduction in Nile tilapia (Oreochromis niloticus) culture systems leads to
overcrowding, poor growth performance, and economic losses. Synthetic androgens such as
17α-methyltestosterone (17α-MT) are effective for sex reversal but raise environmental, food
safety, and regulatory concerns. Plant-based alternatives with endocrine-modulating and healthpromoting properties are therefore increasingly sought. Newly hatched Nile tilapia fry were fed
diets supplemented with graded levels of 17α-MT (25-, 50-, and 75-mL stock solution per 250
g feed) or Aloe vera gel (2.5, 3.75, and 5.0 mL per 250 g feed) for 60 days, followed by a fourmonth grow-out period. Survival, sex ratio, growth performance, feed utilization, antioxidant
enzyme activities, hepatic biochemical indices, and carcass testosterone residues were evaluated
using standard analytical methods. Masculinization increased with increasing inclusion levels
of both agents, with the highest male proportion (>96%) obtained in fish fed 75 mL 17α-MT.
Aloe vera gel achieved high masculinization efficiency (up to ~94%) while significantly
improving survival, antioxidant status, and liver enzyme profiles at lower inclusion levels.
Testosterone residues in A. vera-treated fish remained within acceptable physiological limits
and were lower than values typically associated with synthetic hormone use. Aloe vera gel
represents a viable, eco-friendly alternative to synthetic 17α-methyltestosterone for monosex
Nile tilapia production, offering competitive masculinization efficiency alongside enhanced fish
health and reduced residue-related risks. Its application supports sustainable aquaculture
practices and aligns with emerging regulatory and food safety priorities.