Protein sources, hydrolyzed fish protein concentrate and plasmolyzed lactic yeast, were used to partially replace fish meal and soybean meal, respectively, in a basal diet (diet 1) at these levels; 5% fish protein concentrate + 5% lactic yeast (diet 2), 5% fish protein concentrate (diet 3), and 5% lactic yeast (diet 4). A commercial diet was used as control. Diets were fed to Penaeus monodon postlarvae in an eight-week feeding trial in tanks. Parameters measured to determine diet efficiency were weight gain, survival, mass weight and feed conversion efficiency. Growth rates of shrimp postlarvae fed diets 2 and 4 were similar to those of the basal and commercial diets but significantly higher (P<0.05) than diet 3. On the other hand, diet 3 gave the highest survival rate. This value was significantly higher than the commercial diet but not significantly different (P>0.05) from diets 1, 2, and 4. Performance in terms of mass weights gave no significant differences among treatments. Field-testing of the diets showed that both fish protein concentrate and lactic yeast can support shrimp production in brackishwater ponds.