International Journal of Fisheries and Aquatic Research

Authors
Francis A Anani, Etornam N Tornyeviadzi, Patience DK Atsakpo, Clement K Agyapong, Kelvin K Donkor

Abstract
Early expansion of tilapia culture was limited as tilapia sexually matures at an early age, which results in overcrowding and in stunted growth in culture systems such as ponds and tanks. Methods for culturing exclusively mono-sex male tilapia have been developed to address these problems and until now the commonest of these is by treating hatchling with a male hormone, such as methyl testosterone (MT) or ethyl testosterone (ET) before the primal gonadal cells of females are differentiated into ovarian tissue. The effect of keeping 17α-MT feeds at different ambient temperatures (i.e. refrigerator, room and sun; designated FHF, RHF and SHF respectively) on mono-sex male tilapia fingerling production was investigated. Swim-up Nile tilapia fry at initial mean weight of 0.03 ± 0.00 g were stocked at a density of 1 500 per m³ in 12 hapas, each of dimensions 1.0 x 1.0 x 1.0 m. The hapas were randomly put into four groups, with each consisting of three hapas. Each group of fry was separately fed with each feed type whilst the last group was fed with a non-hormonal feed (NHF) at a two-hour time interval for 28 successive days. The fry were then transferred to 12 larger hapas, each of dimensions 5 x 2 x 1.2 m and they were all fed with a non-hormonal feed at ad libitum until they attained sizes ≥ 20 g for sexing. Percentages of males recorded in FHF, RHF and SHF were similar (90.24 ± 2.01%, 91.34 ± 0.95% and 92.49 ± 0.42% respectively) and they were significantly higher (Tukey’s HSDT, P <. 05) than that (64.90 ± 3.32%) of NHF. Hence, keeping 17α-MT feeds at different ambient temperatures did not have effect on mono-sex male tilapia fingerling production