Lasia (Lasia spinosa (L.) Thwaites) has long been used since ancient time for the treatment of various ailments in man. However, the use of this plant in fish culture as a natural feed additive in fish diets to improve growth rate has not yet been studied. Thus, the aims of this research were conducted to investigate the effects of lasia extract (LSE) on growth performance and intestinal histology of hybrid catfish (Clarias macrocephalus x C. gariepinus). Arial parts of lasia were extracted with 75% ethanol. Preliminary phytochemical screening was examined by using colorimetric assay. Fish with an average of initial weight of 7.00±1.00 g were divided into 4 treatments of 3 replications before being fed diets incorporated with different levels (0, 1, 3 and 5% based on dried weight) of LSE. Fish were fed ad libitum two times a day with a rate of 3% of live body weight for 8 weeks. Phytochemical prospecting of LSE exhibited the presence of flavonoids, terpenoids, phenolic compounds, steroids, saponins, coumarins, glycosides and anthraquinones. After a feeding trial, growth performance and feed utilization efficiencies of fish fed with the experimental diets were significantly improved when compared to the basal diet (P<0.05). Survival rate, intestinosomatic index and condition factor were not affected by the diets (P>0.05). Villi height, villi width, muscularis thickness, microvilli