The main purpose of this study is to find out the possibility of using fermented golden apple snail (FGAS) as an alternative protein source in sex-reversed red tilapia (Oreochromis niloticus x O. mosambicus) diets. FGAS was prepared by incubating minced golden apple snail (GAS) with locally screened lactic acid bacteria and using molasses as carbon sources at ambient temperature for 10 days. Five experimental diets were formulated by replacing fishmeal with FGAS at level of 0 (control), 25, 50,

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... 75 and 100 % of fishmeal protein. Another diet with minced GAS was also included in the experiment. Each diet was randomly fed to triplicate groups of fish with an initial weight of 2.73 ± 0.09 g for 8 weeks. The results showed that growth performance and feed utilization of fish fed 75 % fishmeal replacement diet were significantly better (p < 0.05) than those fed the control diet. The fish fed 100 % replacement diet showed lower growth rates compared with the control diet but were not significantly different (p > 0.05). In addition, fish fed a diet containing minced GAS showed better growth performance and feed utilization than those of the control diet. The digestibility study indicated that fish utilized protein from snail meal either in a minced or fermented form much better than protein from fishmeal. It was concluded that snail meal is a potential protein source in sex-reversed red tilapia diets. Replacement of fishmeal protein with minced snail meal could be at 50 % and FGAS could be up to 100 % but 75 % is recommended.