Preliminary experiment on masculinization of mud crab (Scylla tranquebarica) with 17α-methyl testosterone treatments

Abstract

There is a difference in growth between male and female mud crabs, where males grow faster than females. However, the price of female crabs can be higher than males when female crabs contain eggs which can reach one-third of the whole meat portion. Therefore, the preference for monosex or multi sex cultivation in aquaculture can provide different earnings. Sex reversal has been successfully carried out on various aquaculture fish species, but is yet not common in crustaceans, especially in mud crabs. This preliminary experiment aims to determine the possibility of the masculinization of mud crabs treated with 17α-Methyl Testosterone (MT). The experiments were carried out by the immersion of four-day-old crablets (C-4) with various doses of MT hormones (0, 1, 10, and 100 ppm) for four hours. Following the immersion treatment, crablets reared individually for two months before the male percentage was calculated at the end of the experiments. The result of the experiment showed that immersion with MT hormone solution at a dose of 100 ppm for four hours resulted in total death, whereas no deaths occurred at 0 and 1 ppm. While at 10 ppm treatment, 10% mortality occurred. The MT hormone immersion was found to be ineffective in sex inversion of the C-4 mud crabs where the male sex percentage between treated crab and the control was not significantly different (P>0.05). On the other hand; the second study showed that immersion of C-4 krablet with a dose of 7.5 ppm followed by feeding with MT containing diet for 30 days at 2.5-7.5 mg kg¹ feed resulted in 100% male.