This study was aimed to study the impact of the leached waste (effluent) from the red mud pond of Alumina industry (NALCO) situated at Damonjodi, Koraput on the tissue slice respiration rate of brain, liver, muscle and gill tissues of a fresh water fish, Oreochromis mossambicus, Peters (Tilapia) and its ecological significance. Laboratory acclimatized fresh water fishes were exposed to the sub-lethal dose (3.1%) of the effluent in 50 liters of water in an aquarium for 28th days. Exposed fishes appeared lethargic soon after they were exposed to the toxicant and it was more noticeable after 7th days of exposure, when compared to the control fish. The tissue slice respiration rate of brain, liver, muscle and gill tissues of the exposed fish decreased significantly after 7th days of exposure onwards. The tissue slice respiration rate of different tissues declined significantly with the increase in exposure period and maximum depletion was noted on 28th day of exposure. The exposed fishes were allowed to recover in toxicant free water for 28th days for recovery studies. Significant recovery was not observed in 28th day exposed fishes. During recovery period, the exposed fishes started dying indicating damage done to the metabolic system. The effluent waste significantly affected the respiration rate of the exposed fish indicating the acute toxic nature of the toxicant. The exposed fish could not recover to its pre-test activity even after 56th days of recovery, double the exposure period indicating damage to vital systems. Control fish remained clinically healthy for the entire period of experimentation.