Various anthropogenic activities like introduction of untreated industrial wastes into the aquatic environment, dumping of hospital and other wastes, draining of sewerage and recreational activities have resulted in increased influx of heavy metals and other contaminants in the aquatic environment (Javed, 2012). Due to their stability and persistent nature, heavy metals concentration has indicated increased values continuously in natural water bodies (Rauf et al., 2009). Although water quality monitoring usually involves measurements of physico-chemical variables, biological monitoring has also become important as it exposes the harmful effects of toxicants and could specify threat to environment and human health (Frenzilli et al., 2009). Aluminum is considered third most abundant element on earth after oxygen and silicon. In excess it act as a toxicant causing environmental risks (Atli et al., 2006). Although it is not known to be essential element for the processes of life, it is reported as toxic to a variety of organ systems, including bones, blood, brain and kidney of living beings (Yokel, 2000; Lankoff et al., 2006; Ward et al., 2006). Higher concentration of aluminum resulted in different diseases like bone disturbances, microytic anaemia, Alzheimer’s disease and Parkinson’s disease, encephalopathy and amyotrophic lateral sclerosis (Santibanez et al., 2007; Verstraeten et al., 2008; Bonday, 2010). Moreover, aluminum is also well recognized as pro-oxidant agent promoting biological oxidation (Exley, 2004). It is also responsible for change in the level of antioxidant enzymes and induction of oxidative damage (Zatta et al., 2002; Sinha et al., 2007). Water pollution has plagued throughout Pakistan as predominantly the industrial effluents and domestic sewage comprise major proportions of the toxic chemicals, especially the heavy metals, which are continuously discharged into the water bodies (Javed, 2012). Due to their detrimental effects, aquatic biota suffers intensively and it is necessary to monitor their toxicity to the key edible fish species. Presently, the scenario apparently gives warning signals for the temporal and spatial level of the process, as well as assessment of possible impacts of metal on the human health (Fernandes et al., 2007). The present investigation was therefore conducted to determine the acute toxicity of Al, in terms of 96-h LC50 and lethal concentration, to the four fresh water fish species and responses of different age groups of all the four fish species to metal’s toxicity.