Massive fish mortality events in both marine and freshwater ecosystems pose a threat to the conservation of the elements of aquatic biodiversity and negatively impact fisheries in the Dominican Republic with the consequent economic losses for fishers and their families. This study compiles and analyzes the data and information recorded in news from digital newspapers, videos, government technical reports and interviews with key informants in relation to news source, date and location where the mass mortality happened and perceptions about the possible causes of fish mass mortality. The analysis of 50 ffsh mass mortality events that took place from year 2005-2019 showed that the main marine groups and life cicle affected by mass mortality are juvenile stages of Gerreidae, Holocentridae, Haemulidae, Mugilidae, Tetraodontidae, Anguillidae and invertebrates such as marine crabs. Freshwater fishes including Cichlids (Oreochromis spp. and Nandopsis haitiensis); Cyprinidae (carps), Mugilidae (Agonostomus monticola) and Eleotridae (Eleotris pisonis) are integral parts of the death fish mass architecture as well as a few freshwater crabs, shrimps and turtles. Probable causes of mass fish death are related to poisoning by spillage into the water, spillage or fumigation with toxic chemicals, anoxia related to massive arrival of the Sargassum seaweed or overheating of the waters, fishing with inappropriate nets, practice of "apaleo" or water beating and, in some cases, the causes are unknown. The real and potential effects of massive fish deaths on fishing activity and beach tourism are discussed.