Global Journal of Fisheries Science

The study aimed at determining the effect of sex reversal hormone (17α-methyltestosterone) on the growth performance and survival rate of Heterobranchus longifilis. The experiment consisted of five treatments replicated three times in a completely randomised design. Mature and gravid broodstocks of H. longifilis were purchased and bred in the laboratory to obtain fry that were used for the study. One hundred and fifty (150) fry of the same age (three days), 4 mm in size, were used for the study. The fry was stocked in 15 plastic bowls of 4 litres each at 10 fry per bowl, 30 fry per treatment. The experimental feed (75g) was divided into five equal parts of 15g for the experimental treatments, 20mg of the hormone was dissolved in 75ml of ethanol and was mixed thoroughly with spatula for about 5 minutes and was added to 15g feed each at 1.0ml, 2.0ml, 3.0ml, 4.0ml and 0ml respectively and was mixed thoroughly with 0.5ml Cod liver oil purchased from a pharmacy, to avoid clumps, and then was left to dry under room temperature for 24hours. The dried feeds were labelled as MTSR_0, MTSR₁, MTSR₂, MTSR_3, and MTSR_4, as control, treatment 2, 3, 4 and 5, respectively. The fry was fed 3% body weight with the treated diet for 28 days, after which feeding was continued with normal, untreated formulated fish feed for another 56 days. The result of the study showed that fish fed 17ᾳ-methyltestosterone showed significantly improved growth performance compared to fish fed a diet without 17ᾳ-methyltestosterone. The highest and best growth was observed in fish fed a diet containing 4.0mls 17ᾳ-methyltestosterone with 246.0g, 591.1%, 1.47, 1.84 and 68.03% in weight gain, percentage weight gain, feed conversion ratio, specific growth rate and feed efficiency, respectively. Survival rate was highest 63.33% in MTSR₃ and MTSR₄respectively, followed by 60.00% in MTSR₀ and MTSR₂, respectively. The results of the study further showed that the highest sex occurrence of 89.47% and 78.95% males was recorded in the fish fed experimental diets containing 4.0mls and 3.0mls 17ᾳ-methyltestosterone, respectively, and the lowest 50.00% in the control. The study clearly indicated that the inclusion of 17α-methyltestosterone in the diets significantly altered the sex ratio towards male and enhanced the growth performance in the sex reversed fish.