Abstract
A mixed population of captive born weedy sea dragons (Phyllopteryx taeniolatus) and leafy sea dragons (Phycodurus eques) housed at a public aquaria had been experiencing chronic morbidity and mortality over several months. Clinical signs of affected individuals included: focal areas of eroded epithelium, tail necrosis and lethargy. Maintaining optimal water quality parameters and incorporating various water treatment regimes (long term immersion with erythromycin 50 mg/liter) were not successful at controlling the problem. The individual improved for a short time, dermal lesions decreased in size, then it deteriorated rapidly and died. Skin scrapes of the examined individuals were negative for external parasites. Bacterial cultures from the ulcerative skin lesions grew Staphylococcus sp.
Formalin-fixed specimens of three weedy sea dragons and two leafy sea dragons submitted for histopathology revealed a severe bacterial septicemia involving at least two different bacteria in multiple organs. Bacterial thrombi were located in several vessels and in the heart and gill. Other organs, such as the kidney, hepatopancreas, and heart had discrete granulomas interrupting the normal parenchymal architecture. Special stains (Brown-Hopps, Ziehl Neelsen) confirmed that the predominant bacteria was a gram (+) positive cocci organism which had disseminated to numerous visceral organs, including the heart, gill, hepatopancreas, kidney, intestine, muscle, mesenteric tissues and brain. This gram (+) positive organism was morphologically consistent with the external isolate of Staphylococcus sp. In addition, dispersed among various affected tissues and in discrete granulomas were less numerous gram (+) positive, acid-fast positive organisms. The acid-fast organism was cultured on Lowenstein-Jensen media and fit the criteria of a Mycobacterium sp.
Additional histopathological findings include several metazoan parasites, including mature cestodes in the intestinal tract of one individual and numerous encysted, larval nematodes in the mesenteric cavity of several of the sea dragons. However, no intestinal coccidian infestation or microsporidial skin infestation were noted.1,2
References
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2. Greenwell, MG, AC Fledman, BM Harris, M Dutcher, MJ Kinsel, LS Zwick.. (1999) Clinical and pathological findings from a large collection of syngnathid fishes (seahorses, pipefishes and their relatives). Proceeding of the International Association for Aquatic Animal Medicine. 30: 143-144.
3. Upton SJ, MA Stamper, AL Osborn, SL Mumford, L Zwick, MJ. Kinse, RM Overstreet. (2000). A new species of Eimeria (Apicomplexa, Eimeriidae) from the weedy sea dragon Phyllopteryx taeniolatus (Osteichthyes: Syngnathidae). Diseases of Aquatic Organisms, 43:55-59.