Fish diseases - their symptoms and how to treat them

As many aquarists will know, there are hundreds of bacterial, parasitic and fungal infections that can affect the health and wellbeing of your fish. Contrary to popular belief, fish are highly sensitive animals, and environmental changes, no matter how minor, can trigger periods of stress and illness.

In order to prevent illness, or to prepare yourself should disease or infection become present in your fish tank, you may wish to consider:


  • If you have a large aquarium, you may wish to invest in a small fish tank to set up as a hospital tank. Treating an individual fish in a hospital tank will be both easier and cheaper than treating your whole aquarium.  

  • You will need to remove any activated carbon for the duration of treatment; otherwise it will absorb the medication from the water, making it ineffective.

  • Most fish diseases are the result of stress, and poor water quality plays a large factor in this. The inclusion of a good aquarium filter to maintain optimum water conditions can significantly reduce the risk of disease, as well as regular water changes.

  • Freshwater aquarium salt can be added to your tank to help fish recovering from illness. The electrolytes help to promote good health, heal wounds and reduce stress levels.

  • The regular addition of a multi vitamin treatment can help boost the immunity of your fish and help prevent disease, as well as for those recovering from infection.


Fortunately, most diseases are easily diagnosed and treated, however spotting the signs early is often crucial to recovery.

Outlined below are a number of the more common illnesses to affect freshwater aquarium fish, along with details on their symptoms and advice on how to treat them.

For a full breakdown on the most common fish diseases, visit our blog for more information