Abstract

A hobbyist brought a moribund gray angelfish to our diagnostic laboratory in the fall 1998. He recently purchased the juvenile (118mm TL) from a local aquarium shop and held it in a 55-gallon home aquarium. The wet/dry system was set up for three months with an established population, including a blue angelfish, pygmy angelfish, bursa triggerfish and a small clownfish. The skin coloration of the gray angelfish was pale, with an ulcerative lesion anterior to the anal fin. Gills were pale to mottled and low numbers of Amyloodinium was observed. Bacterial cultures of the lesion, spleen and liver were positive for Vibrio cholerae, but culture of the anterior kidney on Sabouraud's media was negative. Internal examination revealed low to heavy number of multifocal granulomas in the liver, spleen, anterior and posterior kidneys, and mesentery fat. These granulomas were acid-fast negative but silver-positive upon histological examination. The thick, double-walled cysts with multinucleated cytoplasm, evident by the silver stain, were definitive for Ichthyophonus sp. We concluded that this angelfish developed the chronic fungal disease while in the wild, due to the recent collection (approximately two weeks earlier). Handling and possible aggressive behavior on the part of the established tankmates may have contributed to the secondary bacterial infection and its final demise.