Information on Bacterial Disease of Fish
Bacterial Diseases of Fish
by Robert B. Moeller Jr., DVM
California Animal Health and Food Safety Laboratory System
University of California
Aeromonas hydrophila (Bacterial Hemorrhagic Septicemia)
1. Gram negative motile rods
2. Effects many freshwater species and usually is associated with stress and overcrowding.
3. The clinical signs and lesions are variable. The most common finding is hemorrhage in skin, fins, oral cavity and muscles with superficial ulceration of the epidermis. Occasionally cavitary ulcers (similar to A. salmonicida) are observed. Exophthalmus and ascites are commonly observed. Splenomegaly and swollen kidneys are common. Histologically, multifocal areas of necrosis in the spleen, liver, kidney and heart with numerous rod shaped bacteria are observed.
4. Diagnosis is rendered by culturing the organism from affected animals: Remember this is a common water saprophyte with a great variation in virulence in serotypes.
5. Disease is transmitted via contaminated water or diseased fish.
Pseudomonas fluorescens
1. Short motile Gram-negative rods with polar flagella.
2. Lesions similar to Aeromonas hydrophila with a hemorrhagic septicemia resulting in hemorrhage of the fins and tail and ulceration of the skin.
3. Pseudomonas anquilliseptica causes a serious problem in Japanese eels with a septicemia resulting in petechial hemorrhage on fins and tail and ulceration of the skin.
Vibrio
1. Gram negative rod, lives primarily in a marine environment
2. Vibrio septicemia: V. alginolyticus / V. anquillarum / V. salmonicida
1. Septicemia has similar lesions to Aeromonas hydrophila.
2. See hemorrhage in the skin of the tail and fins, ulceration of the skin, hemorrhage in the muscles and serosal surfaces. The spleen may be enlarged and bright red. Histologically may see necrosis of the liver, kidney, spleen and occasionally the gut mucosa.
3. Ulcer Disease of Damselfish: V. damsela
1. Deep skin ulcers and
by Robert B. Moeller Jr., DVM
California Animal Health and Food Safety Laboratory System
University of California
Aeromonas hydrophila (Bacterial Hemorrhagic Septicemia)
1. Gram negative motile rods
2. Effects many freshwater species and usually is associated with stress and overcrowding.
3. The clinical signs and lesions are variable. The most common finding is hemorrhage in skin, fins, oral cavity and muscles with superficial ulceration of the epidermis. Occasionally cavitary ulcers (similar to A. salmonicida) are observed. Exophthalmus and ascites are commonly observed. Splenomegaly and swollen kidneys are common. Histologically, multifocal areas of necrosis in the spleen, liver, kidney and heart with numerous rod shaped bacteria are observed.
4. Diagnosis is rendered by culturing the organism from affected animals: Remember this is a common water saprophyte with a great variation in virulence in serotypes.
5. Disease is transmitted via contaminated water or diseased fish.
Pseudomonas fluorescens
1. Short motile Gram-negative rods with polar flagella.
2. Lesions similar to Aeromonas hydrophila with a hemorrhagic septicemia resulting in hemorrhage of the fins and tail and ulceration of the skin.
3. Pseudomonas anquilliseptica causes a serious problem in Japanese eels with a septicemia resulting in petechial hemorrhage on fins and tail and ulceration of the skin.
Vibrio
1. Gram negative rod, lives primarily in a marine environment
2. Vibrio septicemia: V. alginolyticus / V. anquillarum / V. salmonicida
1. Septicemia has similar lesions to Aeromonas hydrophila.
2. See hemorrhage in the skin of the tail and fins, ulceration of the skin, hemorrhage in the muscles and serosal surfaces. The spleen may be enlarged and bright red. Histologically may see necrosis of the liver, kidney, spleen and occasionally the gut mucosa.
3. Ulcer Disease of Damselfish: V. damsela
1. Deep skin ulcers and
References: 1. Roberts R.J: Fish Pathology, Bailliere Tindall, London, Second edition, 1989. 2 3. Anderson B.G.: Atlas of Trout Histology, Wyoming Department of Fish and Game, 1974. 4 5. Magaki G., Rebelin W.E.: The Pathology of Fishes, The University of Wisconsin Press, 1975. 6 7. Tucker C.S.: Channel Catfish Culture, Elsevier Science Publishers, Amsterdam, 1985. 8 9. Wales J.H.: Microscopic Anatomy of Salmonids. An Atlas, United States Department of the Interior, Resource Publication 150, 1983. 10 11. Reichenbach-Klinke H. H.: Fish Pathology, T.F.H. Publications, Inc. Neptune City, NJ. 1973. 12 13. DeTolla, L.J., Srinivas, S.: "Guidelines for the Care and Use of Fish in Research". Institute of Laboratory Animal Resourses Journal. Vol 37:4(1995), pp 159-173. 14