Difference between revisions of "Branchiomycosis"
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Also known as: '''''Branchiomyces infection — Gill Rot''''' | Also known as: '''''Branchiomyces infection — Gill Rot''''' | ||
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It has been reported primarily in '''Europe''' and Taiwan but also in the southeast USA. | It has been reported primarily in '''Europe''' and Taiwan but also in the southeast USA. | ||
| − | The two most commonly isolated species are '' | + | The two most commonly isolated species are ''B. sanguinis'' and ''B. denigrans'' which have different host specificities and distributions. |
| − | The organism attaches to the gill surface and '''forms hyphae''' which penetrate the tissue and damage the blood supply to the area. '''Spores''' can be released and develop on the floor of the tank in favourable conditions ( | + | The organism attaches to the gill surface and '''forms hyphae''' which penetrate the tissue and damage the blood supply to the area. '''Spores''' can be released and develop on the floor of the tank in favourable conditions (35-32°C, low oxygen, lox pH). |
==Clinical Signs== | ==Clinical Signs== | ||
| − | Infected fish exhibit '''respiratory symptoms''' and a loss of equilibrium | + | Infected fish exhibit '''respiratory symptoms''' and a loss of equilibrium. |
| − | '''Mortalities''' can occur in less than | + | The gill appreas '''necrotic, eroded and pale'''. |
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| + | '''Mortalities''' can occur in less than 48hours and can reach 50% of the herd. | ||
==Diagnosis== | ==Diagnosis== | ||
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'''Wet mounts or histopathology''' of the lesions will enable a diagnosis to be made. Characteristic hyphae within the vessels of the gills or penetrating the gill tissue will be visible. These hyphae are light brown, slightly refractile, branching and non-septate. | '''Wet mounts or histopathology''' of the lesions will enable a diagnosis to be made. Characteristic hyphae within the vessels of the gills or penetrating the gill tissue will be visible. These hyphae are light brown, slightly refractile, branching and non-septate. | ||
| − | '''Special stains''' such as | + | '''Special stains''' such as the GMS can be used to identify the fungal elements. |
''B. denigrans'' appears to affect the entire gill whilst ''B. sanguinis'' is restricted to gill blood vessels. | ''B. denigrans'' appears to affect the entire gill whilst ''B. sanguinis'' is restricted to gill blood vessels. | ||
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There is '''no known treatment''' for the disease but some protocols may be beneficial with malachite green, formalin baths, copper sulphate and benzalkonium chloride dips, and oral methylene blue. | There is '''no known treatment''' for the disease but some protocols may be beneficial with malachite green, formalin baths, copper sulphate and benzalkonium chloride dips, and oral methylene blue. | ||
| − | ''' | + | '''Predisposing factors''' to help control the condition include reducing overcrowding, levels of ammonia, algal blooms, levels of organic material, water temperature and improving hygiene. |
Infected or dead fish should be promptly removed from the tank, pH in the tank can be increased by adding quick lime, and ponds can be drained and limed. | Infected or dead fish should be promptly removed from the tank, pH in the tank can be increased by adding quick lime, and ponds can be drained and limed. | ||
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Revision as of 15:14, 28 September 2011
Also known as: Branchiomyces infection — Gill Rot
Introduction
Branchiomycosis is an acute infection of the gills that can cause high mortality and respiratory distress in many species of ornamental and freshwater fish such as the Koi, the eel, the bass and the perch.
It has been reported primarily in Europe and Taiwan but also in the southeast USA.
The two most commonly isolated species are B. sanguinis and B. denigrans which have different host specificities and distributions.
The organism attaches to the gill surface and forms hyphae which penetrate the tissue and damage the blood supply to the area. Spores can be released and develop on the floor of the tank in favourable conditions (35-32°C, low oxygen, lox pH).
Clinical Signs
Infected fish exhibit respiratory symptoms and a loss of equilibrium.
The gill appreas necrotic, eroded and pale.
Mortalities can occur in less than 48hours and can reach 50% of the herd.
Diagnosis
Gross evaluation of the gills reveals a patchy marbled appearance due to the haemorrhages and necrosis.
Wet mounts or histopathology of the lesions will enable a diagnosis to be made. Characteristic hyphae within the vessels of the gills or penetrating the gill tissue will be visible. These hyphae are light brown, slightly refractile, branching and non-septate.
Special stains such as the GMS can be used to identify the fungal elements.
B. denigrans appears to affect the entire gill whilst B. sanguinis is restricted to gill blood vessels.
Treatment and Control
There is no known treatment for the disease but some protocols may be beneficial with malachite green, formalin baths, copper sulphate and benzalkonium chloride dips, and oral methylene blue.
Predisposing factors to help control the condition include reducing overcrowding, levels of ammonia, algal blooms, levels of organic material, water temperature and improving hygiene.
Infected or dead fish should be promptly removed from the tank, pH in the tank can be increased by adding quick lime, and ponds can be drained and limed.
Fish should be adequately quarantined before being introduced to the tank.
| Branchiomycosis Learning Resources | |
|---|---|
 Test your knowledge using flashcard type questions |
Ornamental Fish Q&A 09 |
References
Noga, E. (2010) Fish Disease: Diagnosis and Treatment Elsevier Health Sciences
Roberts, H. (2009) Fundamentals of Ornamental Fish Health John Wiley and Sons
Lewbart, G. (1998) Self-assessment colour review of Ornamental Fish Manson Publishing