In view of the mass fish mortality in river Beas on May 17, 2018, a team of three scientists namely Dr S. S. Hassan, Dr S.N Datta and Dr M.S Bal from Guru Angad Dev Veterinary and Animal Sciences University,(GADVASU) Ludhiana rushed to the spot on request of Deputy Commissioner, Amritsar Sh. Kamaljit Singh Sangha to assess the probable causes of heavy mortality. According to Dr. K.S. Sandhu, Dean, College of Fisheries, GADVASU, the scientists noticed the brown colour of the following water of the river, apparently due to the flow of sugar factory waste in the form of brown coloured liquid ‘Molasses’ which had affected about 25-30 km of the river stretch. The dead fish species included large sized food fishes like Catfishes and Carps along with some small sized Weed fish like Chela and Puntius etc. The University scientists took a round of the affected river stretch along with the officials of the Punjab Pollution Control Board and Wild Life officials and collected water, sediments and dead fish samples for analysis. Preliminary investigations revealed that the water samples had very poor concentration of dissolved oxygen. The water had acidic pH. It appears that the high fish mortality occurred due to poor availability of dissolved oxygen and acidity of water in a situation of rather than high Biological Oxygen demand. As informed by the local authorities, heavy load of molasses was accidently released in the river water, which has led to lowering dissolved oxygen levels to critical limits, resulting in suffocating conditions along with acid death point (pH 4-5) leading to heavy fish mortality. The collected samples of the sediment, water and fish samples are being subjected to further expediting for toxicological and micro-biological parameters. As per earlier news reports, the freshwater has already been released into the river, which will improve the critical water quality parameters like pH and Dissolved Oxygen and stabilize the conditions.