Abstract:The Artemia nauplii were cultivated with three different conditions, fed with the algae (Platymonas subcordiformis) (E-algae), the yeast (E-yeast), enriched with fish oil (E-oil) for 12 h and a control (starved for 12 h), and then were fed to Oratosquilla kempi larvae. After that, the Ammonia toxicity, Salinity stress, formalin toxicity, starvation tolerance test and digestive enzyme activities (lipase, amylase, Cellulase, Pepsin and tryptase) of different Oratosquilla kempi larvae were examined. The results showed that the tolerances of the E-oil third phase and infant larvae were more elevated than the E-yeast, E-algae and control. Larvae were exposed during 2h to Ammonia, Salinity, formalin and starvation. Based on mortality rates, the median lethal concentration for 50% of the population (LC50) was estimated. As expected from earlier work, larvae fed the optimal diet presented higher n-3 HUFA contents as well as higher Survival and metamorphosis rates. Lipase of the third phase larvae were observed. Higher activities were observed in the E-algae and E-oil larvae which were thrice that of the control. The higher activities of the infant larvae were found in the E-yeast and E-oil, but no lipase activities were found in the E-yeast third phase and E-algae infant larvae, respectively. The highest amylase activities were found in both the E-algae third phase and infant larvae, which were around 69% and 175% higher than the E-oil third phase and infant larvae, respectively. The highest Cellulase activities were observed in the E-yeast third phase and E-oil infant larvae, respectively. The secretion of Pepsin and tryptase were elevated in the E-algae, E-yeast and E-oil infant larvae groups compared to the control, but the highest Pepsin and tryptase activities of the third phase larvae group were found in the control. The digestive enzyme activities and anti-stress test of Oratosquilla kempi larvae were also related to its survival, metamorphic, growth rates and EPA, DHA compositions, proved to be a valuable and important criterion for evaluating the nutritional condition of diets.