This research aims to study the growth rate, FCR, Survival rate, water quality, appropriate amount of garlic extracts for male induction and the production cost of Nile tilapia fed different amounts of food with garlic extract. The experimental design was CRD is divided into 6 treatments with 3 replicates, the control diet (without of 17?-methyltestosterone and garlic extract), Mixed Food 17?- MT and garlic extract diet 25, 50, 75, 100 percent, respectively. The Nile tilapia larvae stage the average weight is 0.01 grams/ aquarium in the size of 25x50x32 cm, density of 3,000 fish/square meter. Feeding the experiment 5 times/day for 28 days. It was found that 50 percent garlic extracts maked Nile tilapia larvae an Average weight gain (gram/fish), Specific growth rates (Percentage/day), Average Daily Gain (gram/fish/day), tend to be better than other treatments. However, 25 percent garlic extracts tended to have the best FCR (2.61?0.14). And 75 percent garlic extracts tended to have the highest survival rate (58.67?3.79). Water quality throughout the experiment was not statistically different. Sex reversal rate found that Nile tilapia larvae fed mixed 17?-MT (99.00?0.89 percent), the highest with statistical significance (p<0.05). In comparison to other treatments. However, 50 percent garlic extracts (89.50?1.00 percent) were similar to the fed mixed 17?-MT. The production cost found that the control was the lowest (0.35?0.01 baht/fish) with no statistically significant difference (p>0.05) when compared with 25, 50 percent with garlic extracts (0.36?0.03 and 0.38?0.01 baht/fish) but, there were statistically different values (p<0.05) when compared to garlic extracts 75, 100 percent and 17?-MT (0.39?0.02, 0.41?0.03 and 0.82?0.02 baht/fish), respectively.
In conclusion, 50 percent garlic extracts tended to have the best growth performance. The 17?-MT was the best sex reversal rate, but the Nile tilapia larvae fed with 50 percent garlic extracts were similar to that experimental. And the control was the lowest value of 0.35?0.01 baht/fish.