Synopsis The Andaman and Nicobar Islands with extensive fringing reefs offer an ideal habitat for a large number of fish species comprising commercial, ornamental, poisonous and venomous nature. Several recent taxonomic studies revealed the existence of more than 1200 species of marine fishes around A & N Islands (Talwar, 1990; Kamla Devi, 1991; Dorairaj et.al., 1994; Rao et. al., 2000). The occurrence of large number of fish species, high dependency of local population on the fish resources and paucity of information on the poisonous and venomous fishes encouraged the authors to study and update the knowledge of these fishes of A & N islands. The rich collections made by the authors from different localities of Andaman Islands and reference collections of Zoological Survey of India, Port Blair comprising 406 examples revealed the occurrence of 147 species belonging to 33 families, known to be harmful due to poisonous and venomous nature when eaten or pose danger while handling them carelessly or catching them by ignorance. The present report includes their taxonomic account along with information on habitat, distribution and the manner in which these fishes are believed to become poisonous or venomous. A brief account on the structure of venom apparatus, toxicity, symptoms and prevention of some poisonous and venomous fishes is given at the end. All the material studied was deposited in the reference collections of Zoological Survey of India, Port Blair.