Guitar shark gill mycosis
Gill fungus is an infection caused by microscopic fungi that settle on the gills of the guitar shark. The gills are the organ that allows this cartilaginous fish to breathe underwater. This disease mainly affects animals kept in captivity,...
What is it?
Gill fungus is an infection caused by microscopic fungi that settle on the gills of the guitar shark. The gills are the organ that allows this cartilaginous fish to breathe underwater. This disease mainly affects animals kept in captivity, in aquariums or ponds, especially when the quality of the water deteriorates. It remains rare but can become serious if it is not treated quickly, because it directly interferes with the animal's breathing.
Key point
Untreated gill damage can quickly progress to serious respiratory distress in this aquatic animal.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
The affected animal breathes faster or irregularly, this is called respiratory difficulty.
It may rub against the walls or floor of the pool, as if trying to relieve an itch in the gills.
Abnormal, slower or disorganized swimming is often observed.
The appetite decreases and the animal becomes more despondent, less reactive than usual.
In advanced cases, the gills may appear discolored, with areas of necrosis (dead tissue) visible on close inspection.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The disease is caused by opportunistic filamentous fungi, i.e. microorganisms naturally present in the aquatic environment but which only become problematic when conditions are favorable for them. They colonize gill tissue that is already weakened, often following stress, injury or a drop in the animal's immune defenses.
Poor quality water, with a high level of organic matter or insufficient filtration, promotes fungal proliferation.
Unsuitable water temperature or sudden variations weaken the animal.
Pond crowding, stress from transportation or handling, and pre-existing injuries to the gills increase the risk.
An immune system weakened by another disease makes the animal more vulnerable.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
The veterinarian specializing in aquatic animals examines the animal, observes its swimming behavior and its breathing.
A sample from the gills can be taken to be analyzed under a microscope or cultured, in order to identify the fungus in question.
The analysis of the pond water is also part of the assessment, because it often focuses on the underlying cause.
Treatment
Treatment is based on antifungals adapted to the aquatic environment, prescribed and dosed only by a specialized veterinarian.
Immediate improvement in water quality (filtration, oxygenation, reduction of organic load) is an integral part of the treatment.
General support of the animal, in particular by reducing environmental stress, is also recommended.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Maintaining excellent water quality is the best prevention: effective filtration, regular monitoring of physicochemical parameters and partial renewal of the water.
It is recommended to avoid overcrowding of pools and to limit sources of stress during handling.
Forty new animals before introduction into a common pool helps reduce the risks of introducing pathogens.
Regular monitoring of the behavior and appearance of the gills allows early detection.
Possible complications
If left untreated, the infection can spread and destroy more gill tissue, seriously compromising the animal's respiratory capacity.
A secondary bacterial infection can be added to already weakened tissues.
In severe cases, respiratory failure can lead to the death of the animal.
When to see a veterinarian
The animal exhibits abnormally rapid or irregular breathing.
It frequently rubs against the walls or bottom of the pool.
A decrease in appetite or unusual depression is observed.
The gills appear discolored or damaged upon observation.
Swimming becomes abnormal, slow or disorganized.
Prognosis
The prognosis is favorable if the disease is detected early and the water quality is quickly corrected in parallel with antifungal treatment.
In the event of late diagnosis or extensive damage to the gills, the prognosis becomes more guarded, as respiratory function may be permanently compromised.
Frequently asked questions
Is gill fungus contagious to other fish in the pond?
The responsible fungi are present in the environment and can affect other weakened animals in the same pond, especially if water quality remains degraded. Monitoring of all occupants is recommended.
Can you treat this disease yourself with aquarium products?
No, a veterinary diagnosis is essential to confirm the fungal origin and choose a suitable treatment. Self-medication can delay treatment and worsen the animal's condition.
How long does the healing take?
The duration varies depending on the severity of the damage and the speed of correction of the water parameters. Only the veterinarian following the animal can give an estimate adapted to the particular case.
Does this disease also affect wild guitar sharks?
It is mainly reported in captivity, where breeding conditions can favor fungal development. In the natural environment, this type of infection remains poorly documented.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
Content reviewed by the TunisieVet editorial team · Updated 25 September 2026
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