400 Journal of Zoo and Wildlife Medicine 34(4): 400–407, 2003 Copyright 2003 by American Association of Zoo Veterinarians ATYPICAL PRESENTATION OF MYCOBACTERIOSIS IN A COLLECTION OF FROGFISH (ANTENNARIUS STRIATUS) Roy P. E. Yanong, V.M.D., Eric W. Curtis, B.S., Scott P. Terrell, D.V.M., Dipl. A.C.V.P., and Gail Case Abstract: Severe systemic mycobacteriosis without typical granuloma formation was diagnosed in a group of six mature, captive, striated frogfish Antennarius striatus approximately 5 mo after fish originating from Brazil were purchased by Mote Marine Laboratory Aquarium. Beginning 1 mo after spawning, over a period of 9 mo, individuals began to show a variety of signs including egg retention, ocular opacity, poor buoyancy control, ascites with coelomic distension, skin lesions, and anorexia. Two fish died, and four were euthanatized. At necropsy, raised pigmented skin nodules; pale pink gills; and pale yellow or tan, fatty livers were noted. A systemic fungal infection was diagnosed histopathologically in one female, and the remaining fish had severe, systemic, histiocytic inflammation and necrosis. Although large numbers of acid-fast bacterial rods were identified in each fish, no bacteria were cultured aerobically from skin, kidney, spleen, liver, or brain. Mycobacterium marinum was cultured from the liver of the last fish that was euthanatized after it became moribund and failed to respond to symptomatic treatment. Key words: Striated frogfish, Antennarius striatus, mycobacteria, atypical, marine, aquarium. INTRODUCTION Piscine mycobacteriosis is typically chronic and affects numerous freshwater and saltwater fish spe- cies. It is caused by many species of atypical, non- tuberculous mycobacteria but usually by Mycobac- terium fortuitum, M. marinum, M. chelonei, or M. abscessus. 3,6,8,9,13,15,18 Clinical signs may include skin discoloration, inappetance, lethargy, abnormal swimming behavior, isolation, cutaneous ulcera- tions or erosions, ascites, reduced growth, and ex- ophthalmia. 2,7,11 Affected fish populations may show chronic low-level mortality. Less-common signs include panophthalmitis, decreased fecundity, skeletal deformities, and melanotic foci in the skin. 1,3,7,12 Additionally, experimentally induced acute disease may be characterized by severe peri- tonitis and necrosis and increased susceptibility to Ichthyophthirius multifiliis infection. 17 Typical gross necropsy findings include prominent small to large, gray to white nodules (granulomas) present in multiple organs, especially the kidneys, liver, and spleen. Histopathology reveals evidence of granu- lomatous inflammation in these organs. 2,3,7,11,12,15,16 From the Tropical Aquaculture Laboratory, Department of Fisheries and Aquatic Sciences, Institute of Food and Agricultural Sciences, University of Florida, 1408 24th Street South East, Ruskin, Florida 33570, USA (Yanong, Curtis); the Department of Pathobiology, College of Vet- erinary Medicine, University of Florida, Gainesville, Flor- ida 32610, USA (Terrell); and the Aquarium, Mote Marine Laboratory, 1600 Ken Thompson Parkway, Sarasota, Flor- ida 34236, USA (Case). Present address (Curtis): John G. Shedd Aquarium, 1200 South Lake Shore Drive, Chicago, Illinois 60605, USA. Correspondence should be directed to Dr. Yanong. This report describes an atypical presentation of mycobacteriosis in six frogfish, Antennarius stria- tus. CASE REPORT A shipment of six approximately 5- to 7.5-cm- long striated frogfish (A. striatus) of undetermined sex were imported from Brazil and sold to Mote Marine Laboratory Aquarium, Sarasota, Florida, in 1999. The fish were placed in two groups for quar- antine. Three of the fish, subsequently determined to include one male (M1) and two females (F1 and F3), were placed in a 151-L tank, and the other three, subsequently identified as two males (M2 and M3) and one female (F2), were placed in a 681-L tank. Each tank had undergravel filtration. The fish were fed a diet of shrimp, squid, and Atlantic sand- lance (Ammodytes spp.). After quarantine the fish remained in their respective tanks. Beginning in April 2000 the frogfish in the 151- L tank began spawning, without any apparent dif- ficulty, every 3 wk. Female 1 (F1) had difficulty in releasing eggs at the end of May 2000. Some of the eggs were removed manually by the veterinar- ian on staff. Female 1 died 4 days later, and the staff veterinarian noted what appeared to be a fatty liver. In August, one group of eggs hatched after 48 hr, although the larvae did not survive. In mid- May, F2 in the 681-L tank showed spawning be- havior. Approximately 2.5 cm of the egg mass was observed protruding from the vent, but she could not release the egg mass. The following day, the nonviable eggs were removed manually, and hem- orrhages were evident around the prolapsed vent. The female was separated from the male by a di- vider and treated with enrofloxacin (Baytril, Bayer,