Use of proviron tablets as source of androgen for sex reversal of Nile tilapia (Oreochromis niloticus, Linnaeus 1758)

The effect of proviron tablets (1a-methyl androsterone) as a masculinization agent was tried on frys of Oreochromis niloticus (Nile Tilapia). 900 Healthy four (4) day old fry of Oreochromis niloticus (D XVII -XVIII, 12-14; A III, 8-10) with mean initial length 1.0cm and mean initial weight 0.0153g were subjected to two feeding treatments. Treatment one (T₁) replicated twice, consisted of 150 fry in a 100L capacity circular plastic basin containing 35 Litres of clean borehole water. Treatment Two (T₂) replicated 4 times contained 150 fry each in similar environment as T₁, however the replicates were fed a starter blended hormone diet containing 60mg of hormone per kilogram of coppens feed. All the treatments were fed at 20% body weight the first week and reduced by 5% weekly till the 4th week. The experimental fishes were transferred from their replicate basins to 6 hapas measuring 1m x 1m x 1m submersed in a concrete pond of dimension 5m x 8m x 1.5m containing algae. The fishes in the hapas fed adlibitum on algae and non-treated 2mm coppens supplementary feed. The result showed that a sample of 164 hormone treated dead fry in the 3rd week following mass mortality were all male. Also when the experiment was terminated in the 9th week all 406 hormone treated fish in 4 hapas were all male (100%). The sex ratio in the 236 untreated fish was 110 males (46.61%) and 126 females (53.39%). The mean weight gain and specific growth rate (SGR) in parenthesis for the sexes in different treatments was: Hormone treated males 4.66g (3.94), untreated males 4.52g (3.92) and untreated females 4.16g (3.87). It was concluded that proviron (la-methylandrosterone) can achieve 100% sex reversal in Oreochromis niloticus and used in place of methyltestosterone, and that hormone treated males grew faster and bigger than untreated males and females. Research on the effect of different doses of proviron on sex reversal of Nile tilapia was recommended.

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