Comparative Growth Performance of Mono-sex and Mixed-sex Nile Tilapia (<i>Oreochromis niloticus</i> L.) in Pond Culture System at Sebeta, Ethiopian

Abstract

Comparative growth performance of hand-sexed male mono-sex and mixed-sex Nile tilapia ( Oreochromis niloticus ) was conducted in six earthen ponds (200 m 2 each) in semi-intensive culture system. Experimental ponds were stocked at a stocking density of 2 fish/m 2 . Fish were cultured for a period of 240 days and fed at a daily rate of 5% of fish body weight. The results of the experiment showed that male mono-sex tilapia showed significantly higher (P<0.05) growth rate (weight, length, DWG, SGR) than mixed-sex group. Generally, male mono-sex fishes reached a larger final individual size (176.20±18.01) g than mixed-sex ((108.20±15.4)g, P<0.05). This difference was more pronounced after the 6 th month during the culture period as the later started reproduction early in the production cycle. Analysis on the economic data indicated that both treatments showed positive net return for the culture periods of 6, 7 and 8 months. However, there was a difference in attaining the optimum net return in culturing Oreochromis niloticus as male mono-sex and mixed-sex. The male mono-sex group attained its optimum net return after 6 months of culture periods, while the mixed-sex group attained after 8 months. Therefore, culturing for extra two months in the later case showed a 32% decline from the optimum net return. Hence growing male mono-sex Oreochromis niloticus for 6 months is profitable under Sebeta, Ethiopia condition.