Abstract

Captive-bred clownfish (Amphiprion clarkii) began exhibiting atypical bottom-sitting behavior at 6.5 months of age. No mortalities occurred but morbidity gradually affected approximately 20% of the 300 fish kept in this 40-gallon closed system. Water chemistry parameters, wet mount biopsies, and routine bacterial culture/sensitivities from necropsied individuals were not remarkable. Routine H&E histologic examination revealed a severe diffuse rhabdomyopathy exhibiting myolysis without concurrent lymphocytic or heterophilic inflammatory infiltrates. Special stains for routine infectious agents were negative. These histopathologic changes are consistent with those found in piscine nutritional muscular dystrophy as reported in other fish species.