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White spot disease (Ich)
White spot disease is a very common parasitic infection in goldfish, caused by a microscopic protozoan parasite. It causes small white spots to appear on the skin, fins, and gills. It is one of the most common and contagious diseases in aqu...
What is it?
White spot disease is a very common parasitic infection in goldfish, caused by a microscopic protozoan parasite. It causes small white spots to appear on the skin, fins, and gills. It is one of the most common and contagious diseases in aquarium fish.
The disease is caused by a microscopic ciliated parasite that burrows under the fish's skin to feed. It thrives particularly well when aquarium water quality is poor or when the fish is weakened. The parasite's life cycle includes a highly contagious free-swimming stage in the water.
Stress from environmental changes, poor water quality, sudden temperature fluctuations, and tank overcrowding increase the risk. Newly introduced fish without a quarantine period are especially at risk. A weakened immune system also favors the development of the disease.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Signs include small white spots resembling grains of salt on the body and fins. The fish may rub against objects in the tank, swim erratically, show clamped fins, and breathe rapidly. Loss of appetite and lethargy are also commonly observed.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Transmission
The parasite spreads easily from one fish to another through contaminated tank water. Introducing a newly infected fish, plants, or undisinfected equipment is a common source of contamination. The parasite multiplies rapidly in a confined environment such as an aquarium.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
If white spots or abnormal behavior appear in your fish, it is important to consult a veterinarian specialized in aquatic animals or an aquarium specialist as soon as possible. Prompt care improves the fish's chances of recovery. Do not attempt self-medication without professional advice.
Prevention
It is advisable to maintain good water quality, stable temperature, and avoid overcrowding the tank. Quarantining any new fish for a few weeks before introduction greatly reduces the risk. Regular filter maintenance and water changes also help prevent the disease.
References
Content reviewed by the TunisieVet editorial team · Updated 08 August 2026
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This information is provided for educational purposes only and is not a substitute for a veterinary consultation. If you have any concerns about your animal's health, consult a veterinarian.
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