During a three-year period, several animals at Mystic Marinelife Aquarium developed local or systemic candidiasis. The results of clinical trials utilizing nystatin, cuprimyxin, ketaconazole alone and in combination with levamisole or levamisole and cimetidine are discussed. The clinical course and gross and histopathologic changes seen in solitary cases of candidiasis in Phocoena phocoena, Delphinapterus leucas, Globicythala melaena, and Tursiops truncatus are compared. Recommendations are given for methods of early detection and treatment.