Gourami with lesion at base of adipose fin


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Jun 23, 2024
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Does this look like a treatable injury/infection or a tumour?
The pectoral fin is also wasting away
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The fish has a minor bacterial infection where the pectoral (side) fin meets the body. Clean water and salt might help but it might need something stronger.

The fish is covered in excess mucous (creamy white film over its body and fins). This is produced by the fish to protect it from something in the water that is irritating the fish.


Check the water quality for ammonia, nitrite, nitrate and pH. Post the test results (in numbers) here.

Wipe the inside of the glass down with a clean fish sponge. This removes the biofilm on the glass and the biofilm will contain lots of harmful bacteria, fungus, protozoans and various other microscopic life forms.

Do a 75% water change and gravel clean the substrate. The water change and gravel cleaning will reduce the number of disease organisms in the water and provide a cleaner environment for the fish to recover in. It also removes a lot of the gunk and this means any medication can work on treating the fish instead of being wasted killing the pathogens in the gunk.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.

Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Wash the filter materials/ media in a bucket of tank water and re-use the media. Tip the bucket of dirty water on the garden/ lawn. Cleaning the filter means less gunk and cleaner water with fewer pathogens so any medication (if needed) will work more effectively on the fish.

Increase surface turbulence/ aeration to maximise the dissolved oxygen in the water.

Add some salt, (see directions below). If there's no improvement after a cleaning the tank and filter and having salt in the tank for 48 hours, you will need something stronger to treat bacteria and fungus. Post move pictures if it gets worse during that time.


You can add rock salt (often sold as aquarium salt), swimming pool salt, or any non iodised salt (sodium chloride) to the aquarium at the dose rate of 2 heaped tablespoon per 20 litres (5 gallons) of water.

Keep the salt level like this for 1 to 2 weeks. If there's no improvement after 48 hours with salt, stop using it and use something stronger. You can do a partial water change before adding new medication or use the medication while the salt is still in the water.

The salt will not affect the beneficial filter bacteria, fish, plants, shrimp or snails.


If you don't have to use a stronger medication, do the following after 2 weeks of salt.
After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

If you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.

When you first add salt, add the salt to a small bucket of tank water and dissolve the salt. Then slowly pour the salt water into the tank near the filter outlet. Add the salt over a couple of minutes.
Thank you Colin for the very complete answer. The numbers are:
Ph 7.0
Ammonia 0
Nitrites 0
Nitrates 0
The numbers aren't as important as a water change schedule. When was the last one?

That reads like a brand new tank where the cycle hasn't kicked in.
It’s a well established tank — over 5 years. I did a 30% water change two days ago.

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