A digestibility study and a growth feeding trial were conducted to study the effect of enzyme supplementation of soybean meal in milkfish diets. Three diets were formulated, namely: diet 1 - a high protein diet (HP) containing 40% crude protein (CP); diet 2 - a low protein diet (LP) containing 30% CP; and diet 3 - is diet 2 plus feed enzyme (LPE). The feed enzyme was a protease to aid soybean digestion in the diet and was added at the rate of 1 kg/ton of feed. Study 1 was undertaken in tanks to determine the milkfish carcass composition, digestibility d the different diets fed to milkfish fingerlings and growth performance of milkfish in tanks. Study 2 was concluded in earthen ponds to determine the effect of the test diets on the growth performance of milkfish after a month culture period. In general, the milkfish carcass on LP diets had higher dry matter content than those on HP diet. However, there was no significant difference in (P, gross energy and phosphorus contents on the carcass of milkfish fed with HP, LP and LPE diets.