Effects of Psidium guajava and Phyllanthus amarus extracts on digestive enzyme activity and growth of Pangasianodon hypophthalmus fingerlings under high-temperature stress

Abstract

The rise in water temperature by global warming is of high concern to aquaculturists. In this study, the effects of extracts-based diets on digestive enzymes, and growth performance in Pangasianodon hypophthalmus fingerlings under elevated temperatures were investigated. Four distinct diets (control, Psidium guajava, (0.2%/kg) – Pg0.2, Phyllanthus amarus (0.5%/kg) – Pa0.5, and a mixture of Pg0.2 and Pa0.5 - Mix.) were administered to fish fingerlings for 42 days, followed by 4 days of temperature elevation. Fish were then continuously subjected for 42 days to temperatures of 27, 31, and 35°C to evaluate enzymatic activities and growth performance of fish. The results showed that although there is no interaction between two experimental factors on digestive enzyme activity and growth performance of fish, Pg0.2 followed by Mix groups accelerated digestive enzymes (trypsin, chymotrypsin, amylases and pepsin). Besides, enzymatic activities increased from 31°C to 35°C. The highest growth was observed from fish at 35°C followed by those at 31°C (p<0.05) which was significantly higher than the control (27°C); however, there was no significant difference in survival rate. In conclusion, these findings suggested 2 appropriate diets (Pg0.2 and Mix) for optimizing growth of this species and consequently contributing to the sustainable aquaculture under the global warming scenario.