This research interest gives a brief about toxic effects of heavy metals and its estimation in aquarium fish. In aquatic ecosystem, heavy metals are considered most important pollutants. Majority of the heavy metals tend to accumulate in tissues as well as in different organs of the body of the fish by consuming polluted water and leads to poisoning of fish. These metals can influence reproduction, growth, weaken the immune system and induce pathological effects. In area of Multan city, water may be contaminated with different heavy metals. The use of this water which is supplied to aquarium, may affect the growth and weight of Tiger barb (Puntius tetrazona). Effect of heavy metals (Chromium and Manganese) on this fish has not determined in area of Multan city. By estimation of Chromium and Manganese metals in this fish has provided very useful way and features for scientists doing work in this domain of effect of heavy metals on aquarium fish. Fish samples were collected from area of Multan city. Each sample of fish (Puntius tetrazona) had passed through Morphometry then calculated the wet and dry weight for each sample. All samples were dried in microwave oven and were grinded to powder. After grinding, samples were subjected for ash formation by Muffle furnace. Then ash of each sample was dissolved in 1%HNO3 to form solution. Then elemental analysis was determined by Atomic Absorption Spectrum. Presence of Chromium and Manganese was confirmed and its effects were determined on Puntius tetrazona by different statistical techniques.