Treatment of an Ulcerative Disease of Bleeding Heart Tetras (Hyphessobrycon erythrostigma)
IAAAM 1991
Roy Yanong1, BA; Sheppard Thorp1, BS; Deborah Gillette2, DVM, PhD; Greg Lewbart3, MS, VMD
1School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA; 2Department of Pathology, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA; 3Greenway Farms, Greenway Road, Naples, FL


The following report describes an ulcerative disease in bleeding heart tetras (Hyphessobrycon erythrostigma) which were imported directly from an exporter in Peru to a holding and quarantine tropical fish facility in Florida. Approximately 3,000 fish arrived in poor physical condition with 30% mortality. Within 12 hours of arrival the fish were fed a commercial flake diet and most accepted the food, but morbidity and mortality remained high. The surviving fish were prophylactically treated with antibiotics on two consecutive days. Approximately 24 hours later, dozens of fish were observed in respiratory distress and close examination revealed ulceration and deterioration of the skin and musculature, especially in the mandibular and subopercular region. Microscopic wet mounts showed the presence of numerous flagellated protozoans attached to and swimming around the mandibular tissue of some of the fish. High magnification (440x) confirmed the presence of the flagellate Ichthyobodo sp. Combined parasiticidal and antibiotic treatment resulted in greatly reduced mortality. Ichthyobodo sp. (still commonly referred to as Costia sp.), a common and serious protozoa parasite of freshwater fishes, is known to cause destructive epithelial lesions with resulting morbidity and mortality. However, in several other ulcerative diseases described in the literature involving different species, parasites play an opportunistic role with the primary pathogen, being Aeromonas salmonicida. This may have been the case in this outbreak as well.


In September of 1990, 3000 Bleeding Heart Tetras (Hyphessobrycon erythrostigma) were imported directly from an exporter in Peru to a holding and quarantine tropical fish facility in Florida. The fish arrived in poor physical condition with 30°/0 mortality. Gross visible lesions were not seen in this group on arrival. Under these circumstances the surviving fish are usually weak and susceptible to disease secondary to the stress of shipping.

The 3000 tetras were floated in plastic bags for 20-30 min. in order to equilibrate their temperature with the system temperature, and then water from the system was mixed slowly with the shipping water over a period of about five minutes to equilibrate water chemistries. The fish and water were poured through nets to exclude shipping water from the system after which the fish were placed into the recirculating system, with approximately 300 fish per 100 liter tank. Dead fish were pulled from the tank immediately. Within 12 hours of arrival the fish were fed a commercial flake diet and most accepted the food but morbidity and mortality remained high--approximately 10%. The system was turned off and surviving fish were treated prophylactically with trimethoprim-sulfamethoxazole at a concentration of 28 ppm for between 6-10 hours on two consecutive days. After each treatment the tanks were drained, refilled and returned to the system. The fish were then fed.

The first day after arrival the remaining fish were examined closely for lesions. The most prominent lesions were ulcerative and involved the mandibular regions of the skin directly ventral to the dentary bones, and subopercular area. Smears of mandibular lesions of several fish demonstrated large numbers of Ichthyobodo.

The second day after arrival the fish were treated with 20 ppm formaldehyde and 28 ppm trimethoprim/sulfa. The majority of fish fared much better and morbidity and mortality were significantly decreased to less than 1%.


Microscopically, there were no apparent lesions involving internal organs (kidney, liver, Gl tract). Gill tissue exhibited necrosis with pyknosis and karyorrhexis, fusion, hemorrhage and inflammation as demonstrated by increased numbers of eosinophilic granulocytes. Ichthyobodo was not seen on gill tissue. Unfortunately, histologic sections of the grossly visible oral lesions were uninformative because so much degeneration had occurred.


Tropical fish captured from the wild for the ornamental fish industry experience numerous stresses which cause reduction in host response to external parasites and other pathogens. These stresses include removal from the natural wild state, handling, transport, overcrowding, hypoxia and poor or different water quality parameters. As soon as host defenses are lowered, pathogens such as Ichthyobodo spp. may take hold and can cause severe morbidity and mortality if left unchecked.

Ichthyobodo are small pyriform flagellated protozoans of the phylum Sarcomastigophora. Among their more prominent features are two posteriorly directed axostyles which are used in feeding and two freely moving flagella which are longer and used for propulsion and host attachment. Two species, I. necatrix and I. pyriformis are known to be causes of Ichthyobodiasis, although I. necatrix is considered the more common of the two. Ichthyobodo uses its flagella and axostyles to penetrate and feed on epithelial cells. This causes destruction of the epithelium of the skin and gills, outer malpighian cell hyperplasia and increased mucus production. Resulting erosions and ulcerations allow access to deeper structure by more opportunistic pathogens. Gills are frequently affected, resulting in respiratory distress. In the fish submitted for histopathology, gills and skin did not show evidence of Ichthyobodiasis, even though different fish from the same shipment had large numbers of Ichthyobodo on wet mounts taken from skin scrapings.

Several other shipments of bleeding heart tetras from Peru (approximately 5 of 10 shipments) presented with similar lesions and clinical course. At least one of these shipments had ulcerative lesions without significant numbers of Ichthyobodo. Interestingly, none of the shipments of this species from Brazil have presented with these lesions (approximately 4 shipments).

A number of different pathogens have been implicated as the cause of erosive and ulcerative lesions. Aeromonas salmonicida has been previously described as the cause of several syndromes affecting freshwater fish.(Bullock, Cipriano, and Snieszko, 1983) Trout ulcer disease is typified by ulcers affecting the fins, jaw, and oral cavity. Goldfish ulcer disease (GUD) caused by atypical A. salmonicida is characterized by dermal necrosis and muscle degeneration. A. salmonicida has also been implicated as the etiologic agent of carp erythrodermatitis. An ulcerative disease caused by A. salmonicida was reported in American eels by Noga and Berkhoff, 1990. Lesions similar to those which we have just described have been seen previously by Gratzek and Shotts in other bleeding heart tetras. (personal communication) Gratzek and Shotts were able to culture Aeromonas salmonicida and believe that this may be the primary cause, with Ichthyobodo as an opportunistic pathogen. This observation is supported by earlier work by Elliot and Shotts which showed A. salmonicida to be a consistent bacterial isolate from early GUD lesions. Ectoparasites, including Ichthyobodo were present but inconsistently. (Elliott and Shotts, 1980)

A variety of other agents and pathogens are also known to cause erosive/ulcerative lesions including hypoxia, net trauma, viruses, and fungi. (Ferguson, 1989)

Our treatment regime of formalin and trimethoprim/sulfa worked well to lower mortality, implying that parasitic and bacterial factors were at work in this particular instance. Hypoxia and net trauma may also have contributed to the lesions in these tetras.


Special thanks to Mr. David O'Beirne, Greenway Farms, for providing the specimens and to Dr. Alan Kelly, University of Pennsylvania School of Veterinary Medicine, for his support of the project.


1.  Bullock, G.L, Cipriano, R.C., and Snieszko, S. F.1983. Furunculosis and other diseases caused by Aeromonas salmonicida. Fish disease leaflet 66, U.S. Dept. of the Interior, Fish and Wildlife Service, Division of Fishery Ecology Research, Washington, D.C. 20240.

2.  Elliott, D.G., and Shotts, E.B., Jr. 1980. Aetiology of an ulcerative disease in goldfish Carassius auratus (L.): microbiological examination of diseased fish from seven locations. Journal of Fish Diseases, 3, 133-143.

3.  Ferguson, H.W.1989. Systemic Pathology of Fish: A Text and Atlas of Comparative Tissue Responses in Diseases of Teleosts. Iowa State University Press, Ames. pp. 4163.

4.  Gratzek, J.B.1988. Parasites Associated with Ornamental Fish. In M.K.Stoskopf, Ed. Tropical Fish Medicine. The Veterinary Clinics of North America, Small Animal Practice. W.B. Saunders, Co., Philadelphia. 18(2):378-385.

5.  Gratzek, J.B. and Shotts, E.B., Jr. 1991. Personal communication.

6.  Noga, E.J. and Berkhoff, H. A.1990. MAAM Proceedings, Volume 21.

7.  Post, G.1987. Textbook of Fish Health. T.F.H. Publications, Neptune City, NJ. 288 pp.

8.  Robertson, D.A., Roberts, R.J., and Bullock, A. M.1981 Pathogenesis and autoradiographic studies of the epidermis of salmonids infested with Ichthyebodo necator (Henneguy, 1883). Journal of Fish Diseases, 4, 113-125.

Speaker Information
(click the speaker's name to view other papers and abstracts submitted by this speaker)

Roy P.E. Yanong, BA, VMD
Tropical Aquaculture Laboratory, Department of Fisheries and Aquatic Sciences
University of Florida
Ruskin, FL, USA

MAIN : Parasitology : Ulcerative Disease
Powered By VIN