Background: The high density of farmed snakehead fish and the expansion of the farming area might cause a negative impact on water environment and an increased frequency of fish diseases. The use of plant-based extracts has been promised as an alternative method to antibiotic application in the controlling of fish diseases. This study was conducted to investigate the effect of Pleurotus ostreatus extract on survival, growth, immune responses and against Aeromonas hydrophila of snakehead fish (Channa striata). Methods: During 2021-11 to 2022-10, the P. ostreatus extract was prepared using hot water method and the fish fed diets supplemented the extract at 0.0 g kg-1, 1.5 g kg-1, 2.5 g kg-1, 3.5 g kg-1 and 4.5 g kg-1 was examined for survival rates, growth responses, white blood cell count, respiratory burst activity and mortality rates of fish in A. hydrophila infection. Result: The results indicated snakehead fish fed five different diets showed no significant differences in survival and growth performances. However, the innate immune parameters were likely increased in fish fed diets supplemented P. ostreatus extract and the diet supplemented extract at 4.5 g kg-1 could reduce the accumulate mortality of snakehead fish challenged with A. hydrophila. P. ostreatus extract could be a promising material for enhancing the innate immunity of snakehead fish and can protect fish from A. hydrophila infection.

This study investigated the effects of replacing fish meal with Leucaena leucocephala leaf powder on survival, growth performance, digestive enzyme activities, biochemical body composition and muscle texture of the whiteleg shrimp (Penaeus vannamei Boone, 1931). Five different diets were examined, by replacing fish meal with L. leucocephala leaf powder at 0, 5, 10, 15 and 20%, in triplicates. Shrimps were stocked in 0.5 m3 tanks @ 70 shrimps per tank and fed on the experimental diets for a period of 60 days. The results showed that the survival rate (%), daily weight gain (g day-1), specific growth rate (% day-1), feed intake (% fish-1 day-1), feed conversion ratio, protein efficiency ratio, and protein retention were not significantly different (p>0,05) among the treatment groups. The values of α-amylase and pepsin in the stomach and chymotrypsin (mU min-1 mg protein-1) in the intestine were not significantly different among treatments. However, the value of α-amylase in the intestine was significantly higher in animals fed diets that replaced fish meal with L. leucocephala leaf powder at 0, 5 and 10% compared to other treatments. The biochemical constituents (except for lipid) and the texture (N) of shrimp meat were not significantly different among treatment groups. The results suggested that L. leucocephala leaf powder could replace fish meal up to 20% in white-leg shrimp diets. Keywords: Digestive enzyme, Growth, Leucaena leucocephala, White-leg shrimp