Fish tank granuloma.

Mycobacterium marinum is an opportunist pathogen commonly found in aquatic environments. Infected fish may develop a disseminated granulomatous disease-fish tuberculosis-that leads to wasting and ultimately to death. In humans this organism causes local infection after contamination of open wounds or abrasions. M marinum skin infection acquired from tropical fish tanks was first described in 1962 by Swift and Cohen,' and has since been reported by many workers world wide.2 M marinum is the causative organism in swimming pool granuloma, which is well known in the United Kingdom3; infections of humans with M marinum after fishing, boating, and other exposure to salt and brackish water has also been described.47 We report on four patients who were diagnosed as having M marinum infection causing tropical fish tank granuloma over eight months in 1988. There had been no other cases locally in the previous five years. Epidemiologically there was no link among the cases.