The rising interest in using alternative livestock feed sources is mostly driven by the rising cost of commercial feed and the desire for agricultural sustainability. This research was conducted to determine the growth performance of Mallard ducks fed with a commercial diet substituted with varying amounts of golden apple snail (Pomecea canaliculata) meal. The study utilized 125 Philippine Mallard Ducks (Itik-pinas kayumanggi) randomly distributed into five treatments replicated five times with five ducks per replicate. This experiment follows a Completely Randomized Design Set-up. The experimental treatments are as follows, GASM0 (Control) -100% commercial mash diet, GASM10 (90% commercial mash diet+10% GAS meal), GASM20 (80% commercial mash diet+20% GAS meal), GASM30 (70% commercial mash+30% GAS meal), and GASM40 (60% commercial mash+40% GAS meal). The results showed that the incorporation of the GAS meal into the diet has significantly improved (p<0.05) the body weight gain. Moreover, GASM30 with 70% commercial mash+30% GAS meal showed a significant improvement (p<0.05) in terms the overall growth performance. The findings indicated that the substitution level of 30% of the GAS meal might result in the efficient growth performance of mallard duck.