Sunken Belly Disease - What is it & how to treat it!

Sunken Belly Disease


Aquarium hobbyists who take extra care looking after fish and the environmental conditions rarely will encounter fish diseases, however, there is no guarantee your beloved fish will not get sick. It is important to have stable water chemistry and, perform frequent monitoring of behaviour and look out for any signs and symptoms of aquatic diseases.


What is it & what causes it?

Sunken belly disease is highly contagious and fatal to aquatic fish. It is caused by an internal bacterial or protozoan (parasite) infection or intestinal worms that enters the fish. The internal protozoan infection and worms are what causes the fish to become skinny and lethargic. Once infected it can take only 7-14 days to kill the fish. It is quite common in cichlids.

It can live on the surface of uneaten food or dead fish that have not been removed from the water. Lack of proper protein and nutrition and poor water quality is also linked to sunken belly disease. Diet is vital for preventing diseases and helping in fighting against them if your fish were to become infected. Poor food is also linked to poor water quality as the food deteriorates in the water.


Signs and symptoms


  • Look very fat/pregnant from bloating
  • Can become skinny due to not eating properly, but still bloated
  • Scales can sometimes be seen sticking out


  • Loss of appetite
  • Weak appearance/lethargic
  • Become pale and anaemic
  • Breathing rapidly
  • Spending time near the filter or surface



If possible, always treat sick fish in a separate tank and quarantine them. As soon as you see any of the above signs and symptoms you must start the treatment for your fish.

Before treating you need to consider if you are going to treat your entire aquarium or isolate fish and specifically treat the sick fish.

For severe outbreak, it is recommended to use antibiotic treatment such as metronidazole and praziquantel. They are highly effective and can be added even before signs and symptoms show. When using this method, you will need to monitor the ammonia and nitrite levels in the aquarium as the treatment can kill the beneficial bacteria in the water.

When you isolate the fish, you can use medicated food and it is the best way to directly impact the parasite that has infected the fish. If you suspect internal parasites in the aquarium, you can mix 1 tbsp of Epsom salt per 4 litres and add to the water. 



As with any fish diseases, combatting any stress should be your top priority. Stress comes from many factors, not just parasites themselves. Always ensure you have the best water quality conditions in your aquarium, check equipment regularly and carry out any maintenance if needed. Never overcrowd your tank as this increases stress and aggression.

Always feed your fish with the best species-specific food so their immune system does not become suppressed. Be familiar with the signs and symptoms so you can recognise the disease early.

Using the product Super Fix (which can be purchased here online) can be used to assist healing when fish become infected with sunken belly disease. This product contains anti-mutagenic, DNA protecting properties which improves the immune system, assists in self worming, reduces the stress of display stock, and can reduce fish loss. It contains locally sourced ingredients and is safe to use with a variety of aquatic fish, plus it can assist fish with many other known aquatic diseases. Head on over to the shop or product info tab to check it out!

Thank you again for reading, we hope to see you again, take care!