Listeria monocytogenes is considered to be a ubiquitous organism occurring in both terrestrial and aquatic habitats. This organism has been isolated from fish and fishery products from different parts of the world and interestingly the incidence rate reported from tropical fish is rather low. Varying methodologies have been used by different investigators to study the incidence of L. monocytogenes in fish. Data on virulence of seafood-associated strains are lacking. For quality assurance in the fish processing industry, rapid and sensitive methods for the detection of L. monocytogenes are required. (C) 2000 Elsevier Science B.V. All rights reserved.