Fish are popular pets for time-poor people. But things can go wrong with pet fish.

If you have a sick fish, or one that has died, it's tempting to medicate the tank. However, certain medications can be toxic to species. The best thing is to take the fish straight to a fish vet.

Fungal diseases

Healthy fish have a mucus covering that prevents them from infection, but if the fish become injured or stressed, fungus can take hold. While the ‘cotton wool' appearance may not look serious, fungus eats away at the flesh.

Parasitic diseases

Protozoal diseases are the most common parasites. A common disease is white spot, where the fish is covered in tiny white lesions.
If unchecked, this can be deadly.

Bacterial infections

Bacteria are always in the tank but harmless unless the fish is stressed. Some indications of bacterial disease include open sores and ulcers.

What to do at home in an emergency

• Test water quality - ammonia, nitrate and pH.
• Change 20 to 30 per cent of the water in order to dilute poor-quality conditions. Refilling with treated water is the most effective method. 
• Add non-iodinised salt (rock or sea salt) to freshwater tanks at an initial concentration of 1g to 2g per litre of water to reduce stress.
• Improve water aeration with an air stone. 
• Stop feeding your fish until a cause for its illness has been established.
• Avoid handling your fish. Seek veterinary help.
• Don't add medications indiscriminately. The misuse of medication can cause more stress.

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