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How To Treat Angelfish For Fin Rot!

Fin rot is an unpleasant condition, and it can be particularly problematic if you keep fish with large, delicate fins, such as angelfish.

While these fish make very beautiful additions to any aquarium, you must know how to look after them and ensure that their needs are met, and this includes looking out for signs of fin rot.

Angelfish fin rot can be very serious and beyond just destroying the aesthetic of these fish, it will cause inflammation and unnecessary suffering.

Fin rot is caused by a few different strains of bacteria, known as Vibrio, Aeromonas, or Pseudomonas, and all of these can be dangerous and contagious.

Knowing which has caused the issue is not as important as making sure that you treat it promptly before it kills the infected fish or spreads to others in the tank.

The damage caused by fin rot can also expose your fish to other fungal infections, so swift action is crucial for the health of the tank as a whole.

Don’t ignore signs of fin rot, because these can almost always be dealt with and will usually have a direct cause within the tank, which means that you can reverse the issue.

In really serious cases, fin rot could kill your fish, so make sure that you identify the cause and implement changes as soon as possible.

What Causes Fin Rot On Angelfish?

Fin rot can be caused by a few different things, but it is most commonly due to poor water conditions allowing bacteria and fungus to thrive within the tank; these will then attack the fish and start to damage their fins.

In some circumstances, a high pH level, cold water, or nibbling by other fish can increase the risks of fin rot among angelfish, but usually, water quality will be responsible.

You should always aim to keep your tank clean and use a suitable filter to ensure that bacteria cannot spread through it.

Often, fish that are stressed will be a lot more vulnerable to fin rot, so it’s really important to ensure that you do what you can to minimize stress, especially when you are adding new fish to your aquarium.

Do not overcrowd the aquarium, and make sure you provide plenty of hideaways, plants, rocks, caves, and fresh food to the inhabitants. Avoid handling the fish unnecessarily, and do not keep incompatible species together, or you will invite these sorts of issues.

High levels of chlorine, ammonia, or nitrites will all cause health problems, so make sure you test for and deal with these.

It is also a good idea to look out for any signs of fish bullying each other, and to separate fish that are causing issues. 

How Can You Identify Fin Rot On Angelfish?

Fin rot is usually fairly easy to identify once you know what to look for; it starts as a milky discoloration at the edges of the fish’s fins, and on angelfish, this can be quite pronounced because they have large fins.

However, it is not uncommon for fin rot to go unnoticed until it starts to cause fraying; this occurs because small pieces of the skin will be dying and tearing away from the main fin.

You may see inflammation following this, as the skin becomes red and bloody where the dead skin is tearing away.

This will progress and the fish’s fins will become gradually shorter and more ragged. Fin rot may move onto the fish’s main body if it is not treated, causing the skin to flake away and become red and sore.

You should take action long before it reaches this point, but it’s worth being aware that this sort of infection can expose the fish to other bacterial infections, such as the cotton-wool bacteria (Columnaris).

You will need to treat the fish as soon as possible to slow and reverse the progression.

Fin rot can cause inflammation and swelling to appear at the base of the fish’s fins, near its body, and it is possible for the fish to lose its entire fin if the issue is not addressed. Be vigilant and treat infections quickly.

How Can You Treat Fin Rot On Angelfish?

You can use antibiotics to treat fin rot in angelfish, but it’s important to do this at the same time as addressing the underlying causes; the water quality must be improved and the sources of stress removed, or the infection will probably just reoccur.

Clean any old food out of the tank and avoid overfeeding in the future, and relocate fish to another tank if you have overcrowding problems. Check all the water parameters and correct any readings that are too high or too low.

Remember that you should also check the temperature and the pH value to ensure the water is suitable for each kind of fish you are keeping, and if you have fish with vastly different requirements, relocate one kind to a separate aquarium.

Don’t leave fish in a tank that is unsuitable, because they will become vulnerable to diseases, and could spread these to the healthy fish in the tank too.

It’s also a good idea to make sure that the food you are giving your fish is fresh, because the level of vitamins in the food will soon go down, and this will leave your fish more vulnerable to diseases.

Put a date on the food and buy it in reasonably small quantities to reduce the risk of it going stale. If you think one of your fish is sick, consult a vet before treating it with antibiotics, and in the meantime, do everything you can to ensure the tank is clean and suitable.


Angelfish fin rot can be an unpleasant and alarming thing to see, but it is something that you should look out for, as these fish are vulnerable to it, and it could kill them. You can minimize their risk of being infected by providing them with the right conditions, removing any fish that are nibbling at their fins, and reducing any sources of stress. If one of your angelfish does get fin rot, take swift action to prevent this from spreading.