2. Definition:Definition:
It is a fungal disease involving gill tissues,It is a fungal disease involving gill tissues,
affecting the most species of freshwateraffecting the most species of freshwater
fish. The disease is causedfish. The disease is caused
byby BranchiomycesBranchiomyces
sanguinissanguinis andand Branchiomyces demigransBranchiomyces demigrans..
It is characterized by areas of infarctiveIt is characterized by areas of infarctive
necrosis of the gills, anorexia, andnecrosis of the gills, anorexia, and
marbling appearance of the gills.marbling appearance of the gills.
3. BranchiomycosisBranchiomycosis
of fish: A -of fish: A -
branching hyphaebranching hyphae
of the fungusof the fungus
BranchiomycesBranchiomyces
sanguinissanguinis
B - fungus hyphaeB - fungus hyphae
spreading in thespreading in the
branchial bloodbranchial blood
circulation, ...circulation, ...
..
4. Causative agent:Causative agent:
There are two species from genus Branchiomyes, which areThere are two species from genus Branchiomyes, which are
responsible for occurrence of the disease.responsible for occurrence of the disease.
1.1. B. sanguinisB. sanguinis: It grows mainly in the blood vessels of: It grows mainly in the blood vessels of
gill arches, filaments and in the gill lamellae.gill arches, filaments and in the gill lamellae.
2.2. B. demigransB. demigrans: This fungal species is found in the: This fungal species is found in the
parenchymal tissues of the gills.parenchymal tissues of the gills.
Both species produce branched and non-septate hyphae.Both species produce branched and non-septate hyphae.
The fungi grow at temperature between 14 and 35C. TheThe fungi grow at temperature between 14 and 35C. The
optimun growth temperature appears to be between 25optimun growth temperature appears to be between 25
and 32C. The fungi grow on Sabouraud's dextrose agarand 32C. The fungi grow on Sabouraud's dextrose agar
medium.medium.
5. Stress factors:Stress factors:
1.1. Elevation of the waterElevation of the water
temperature above 20C.temperature above 20C.
2.2. Low dissolved oxygen.Low dissolved oxygen.
3.3. Reduced water flow.Reduced water flow.
4.4. Over crowded conditions.Over crowded conditions.
5.5. High levels of nutrients in theHigh levels of nutrients in the
water and phytoplankton blooms.water and phytoplankton blooms.
6. Susceptible species:Susceptible species:
The most species of freshwaterThe most species of freshwater
fishes are susceptible tofishes are susceptible to
branchiomycosis.branchiomycosis.
Mode of transmission:
Fungal spores are transmitted by water to gills. These
spores adhere to the gills, germinate and produce
hyphae.
The hyphae penetrate gills epithelium or within the
blood vessels of gills depending on species of fungi.
7. Incubation period:Incubation period:
Incubation period for disease is related to waterIncubation period for disease is related to water
temperature. The disease has been rapidly developed withintemperature. The disease has been rapidly developed within
2-4 days under suitable conditions.2-4 days under suitable conditions.
Clinical signs:Clinical signs:
1.1. Fish become weak in movement.Fish become weak in movement.
2.2. Fish are gathered in groups at water inlet and die.Fish are gathered in groups at water inlet and die.
3.3. Fish do not react to the approach of man and can beFish do not react to the approach of man and can be
caught by hand.caught by hand.
4.4. There are respiratory distress in infected fish and doThere are respiratory distress in infected fish and do
not swallow the air.not swallow the air.
5.5. Fungus develops on or in gill tissue, or penetrates theFungus develops on or in gill tissue, or penetrates the
blood vessels causing obstruction, congestion and necrosisblood vessels causing obstruction, congestion and necrosis
of gill tissues.of gill tissues.
6.6. Gills may be appearing red from impaired circulation.Gills may be appearing red from impaired circulation.
7.7. Subacute form of branchiomycosis characterized bySubacute form of branchiomycosis characterized by
marbling appearance of the gills due to pale anemic patchesmarbling appearance of the gills due to pale anemic patches
in contact with red congested one due to disturbance ofin contact with red congested one due to disturbance of
circulation in gills.circulation in gills.
8. Carp with branchiomycosis (gillCarp with branchiomycosis (gill
mycosis )mycosis )
10. Diagnosis:Diagnosis:
1.1. Case history.Case history.
2.2. Clinical signs.Clinical signs.
3.3. Microscopical examination ofMicroscopical examination of
wet preparation from infected gill.wet preparation from infected gill.
4.4. Isolation and identification ofIsolation and identification of
the causative agent.the causative agent.
11. Prognosis:Prognosis:
Morbidity rate among fishMorbidity rate among fish
populations with epizootics ofpopulations with epizootics of
brachiomycosis usually reach 100%brachiomycosis usually reach 100%
depending on fish species anddepending on fish species and
susceptibility. Mortality rate maysusceptibility. Mortality rate may
each 30 to 50% of the fisheach 30 to 50% of the fish
population during late summerpopulation during late summer
epizootics.epizootics.
12. Treatment and control:Treatment and control:
1.1. Strict sanitation and disinfection are essential forStrict sanitation and disinfection are essential for
disease control.disease control.
2.2. Dead fishes should be collected and daily and burnedDead fishes should be collected and daily and burned
or deeply buried.or deeply buried.
3.3. Ponds with enzootic branchiomycosis should be driedPonds with enzootic branchiomycosis should be dried
and treated with calcium oxide (quicklime) or 2 to 3 kgand treated with calcium oxide (quicklime) or 2 to 3 kg
copper sulphate per hectare.copper sulphate per hectare.
4.4. Diseased fish can be treated with malachite green atDiseased fish can be treated with malachite green at
0.1mg/l for extended periods of time or 0.3mg/l for 120.1mg/l for extended periods of time or 0.3mg/l for 12
hours.hours.
5.5. Transportation of infected fish areas to non-infectedTransportation of infected fish areas to non-infected
areas must be prevents.areas must be prevents.
6.6. Increase of water supply help in control of thatIncrease of water supply help in control of that
disease.disease.
7.7. Stress factors must be avoided.Stress factors must be avoided.
8.8. Regulating the feeding rate during warm weather.Regulating the feeding rate during warm weather.
