The potential effects of 17-alpha-methyltestosterone on toad (sclerophrys regularis) population in fish ponds

Abstract

Nile tilapia (Oreochromis nilitocus) 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. Hormonal sex reversal is the most commonly used method in the production of monosex Nile tilapia. The 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 was fed on feeds having 17-alphamethyltestosterone while the control was fed on hormone-free feeds. The experiment lasted for 28 days. The weights of tadpoles were taken on days 0,18 and 28 postexposure. All results were analyzed using SPSS version 20 and descriptive statistics was used to obtain the mean and standard error means of the variables in the two groups. A T-test was used to compare variables in 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. It can be concluded that 17-α-methyltestosterone could potentially affect the toad populations in the environment where Nile tilapia sexual reversal using hormones is carried out