The growth, survival, and trypsin activity response of Penaeus semisulcatus larvae was examined with two different live feed regimes throughout larval development under laboratory conditions. In the first feeding regime, larvae were fed standard live diets of mixed microalgae from the first to the third protozoea (PZ1 to PZ3), followed by Artemia nauplii until postlarva 1 (PL1). In the second feeding regime, larvae were fed a diet of Artemia nauplii at the beginning of the PZ2 stage. Like other penaeids, P. semisulcatus larvae showed high trypsin activity during the late protozoeal or early mysis stages, which decreased during subsequent stages when fed on conventional live diets of microalgae followed by Artemia nauplii during the mysis stages. P semisulcatus larvae fed Artemia nauplii from PZ2 onward were significantly heavier on reaching M1 than those fed microalgae (P < 0.05). In contrast, the survival rate of larvae fed with the first feeding regime was higher than that of those in the second feeding regime (P < 0.05). The trypsin activity level in stages PZ2, PZ3, M1, and M2 fed Artemia nauplii was significantly lower than that in the same stages fed microalgae (P < 0.05).