Here's why:
* Spores: Saprolegnia spreads through spores that are released into the water. These spores can easily infect other fish, especially those that are already weakened or have open wounds.
* Stress: Stress from poor water quality, overcrowding, or other illnesses can make fish more susceptible to fungal infections.
* Contact: Direct contact with an infected fish can also transmit the fungus.
What to do if your fish has cotton fungus:
* Isolate the infected fish: Immediately remove the infected fish from the main tank to prevent the spread of the fungus.
* Treat the infected fish: Use a fungicide specifically designed for Saprolegnia. Follow the instructions carefully.
* Treat the main tank: Treat the main tank with a fungicide as well. This will help kill any spores that may be present.
* Improve water quality: Ensure good water quality in both the isolation tank and the main tank. This includes regular water changes, proper filtration, and appropriate temperature.
Prevention:
* Maintain good water quality: This is the most important step in preventing fungal infections.
* Avoid overcrowding: Overcrowding can stress fish and make them more susceptible to infections.
* Quarantine new fish: Always quarantine new fish before adding them to your main tank to prevent the introduction of diseases.
By taking these precautions, you can help to minimize the risk of cotton-like fungus spreading in your aquarium.