Batfish case report highlights aquarium mycobacteriosis risk

A new case report in Veterinary Sciences describes systemic granulomatous mycobacteriosis in an orbiculate batfish (Platax orbicularis) from an aquarium in South Korea, with lesions linked by histopathology, acid-fast staining, and partial 16S rRNA sequencing to a Mycobacterium marinum-like organism. The fish had multifocal nodular lesions in the gills, spleen, kidney, and other internal organs, and the authors framed the finding as a diagnosis of chronic systemic mycobacterial disease in a species with little published literature on this condition. Broader fish health literature shows M. marinum is one of the non-tuberculous mycobacteria most often associated with disease in aquarium and farmed fish, and that diagnosis often relies on pathology plus molecular testing because culture can be slow and difficult. (merckvetmanual.com)

Why it matters: For veterinary professionals working with aquatic species, the report is a reminder that unexplained chronic wasting, nodular lesions, or multisystem granulomatous inflammation in ornamental marine fish should keep mycobacteriosis on the differential list. It also carries occupational health relevance: M. marinum and related fish-associated mycobacteria are zoonotic and can cause so-called aquarium or fish tank granuloma in people exposed through damaged skin during tank maintenance, necropsy, or handling of infected fish and contaminated water. (mdpi.com)

What to watch: Watch for follow-up reports on whether additional cases emerge in captive batfish, and whether future work confirms the organism to species level and traces any environmental reservoir within aquarium systems. (mdpi.com)