Nile tilapia is among the various fish species reared in cages, pens, and ponds. However, the major drawback of tilapia pond culture is the high level of uncontrolled breeding that occurs in grow-out ponds. This results in the population surge of stocked tilapia ponds and leads to stunted growth because of the crowding of the fish. Among other techniques that have been used to control tilapia overpopulation is the use of monosex all-male tilapia culture. Hormone 17-alpha-methyltestosterone is commonly used in the sex reversal of Nile tilapia. However, it is not clear how these hormones interact with other organisms in the ponds. The study aimed to assess the potential effects of 17-alpha-methyltestosterone on the growth of the tadpoles bred in the same pond.
Tadpoles were divided into two groups; the control and the exposed group. The exposed group fed on feeds having 17-alpha-methyltestosterone while the control fed on hormone-free feeds for 28 days. The weights of tadpoles were taken on days 0,18 and 28 of exposure. Descriptive statistics was used to obtain the mean and standard error means of the variables in the two groups. Independent sample t-tests were used to compare the two groups at a 5% level of significance.
It was observed that 17-alpha-methyltestosterone had effects on the size and weight of the toadlets. The low variability observed in exposed population suggests tadpole in the hormone exposed group underwent sex reversal. We suggest 17-α-methyltestosterone hormone can potentially affect the toad populations in the environment where Nile tilapia sex reversal is conducted using hormones.
Keywords: Toad population, Nile tilapia, sex reversal, androgens