Acute toxicity tests (96-hr LC₅₀ and lethal concentration) of aluminium (Al) were conducted with three fish species viz. Catla catla, Labeo rohita and Cirrhina mrigala of 60, 120 and 240 days age groups at constant water temperature (30^oC), pH (7.50) and total hardness (300 mg.L^-1) in the wet laboratory. At termination of each trial, the fish were dissected and their organs viz. bones, gills, gut, intestine, kidney, liver, scales, skin, muscles and fats isolated for the determination of Al concentrations. At 60 days, all the three fish species showed significantly (P<0.05) higher sensitivity to Al while 240 days fish were significantly least sensitive. Among the three fish species, Catla catla were significantly (P<0.05) more sensitivity to Al with the mean 96-hr LC₅₀ and lethal concentration of 81.68±28.54 and 129.81±30.95 mg.L^-1, respectively. Fish organs showed significantly variable ability to concentrate metal during acute exposure of Al. However, liver and kidneys exhibited significantly higher potentials for metals accumulation. From the study it was concluded that all the three fish species responded differently towards Al toxicity.

Key words: Acute, Aluminium, Bioaccumulation, Catla catla, Cirrhina mrigala, Labeo rohita