Care & Treatment of Fin Rot

Fin Rot is one of the most common, yet preventable aquarium fish diseases. It often occurs simultaneously with other diseases and is caused by a bacterial infection.

Fin Rot Symptoms

One of the earliest symptoms is ragged fins. As the disease progresses, the fins become increasingly shorter and some whiteness appears on the edges. Cotton Wool, a secondary disease, may develop, and will manifest as a fuzzy growth on the fins. If untreated, the base of the fins will become red and inflamed, with spotty, bloody patches.

Fin Rot Causes

Fin Rot occurs when the Betta is distressed due to poor water conditions, overfeeding, uneaten food, overcrowding or rough handling. If the water is not changed regularly, the leftover food particles and feces will decompose and contaminate the water. If there are too many Bettas or too much food in the tank, even regular water changes may not prevent the disease. The resultant stress on the Betta lowers his immunity, thus making him very susceptible to attack from the bacteria present in the water. Only in rare instances will Bettas develop Fin Rot when a tank is impeccably maintained.

Fin Rot Treatment

First aid kit

Once Fin Rot sets in, change the water and examine the conditions within the aquarium. Remove everything from the aquarium and wash all the decorations and rocks with hot water. Do not use soap. Follow instructions for changing the water in the aquarium.

Since Fin Rot is a bacterial infection, medication is available to cure it. Some medications successfully used to cure fin rot include Jungle Fungus Eliminator and Tetracycline.

Fin Rot is very contagious. Separate the fish that appear uncontaminated from the diseased fish. Place the uncontaminated Betta in a separate quarantine tank until you are sure they are healthy. To prevent the disease from being transferred to your healthy Betta, do not share nets between the tanks. Also, ensure that you wash everything used in handling either the sick or the quarantined Betta properly in hot water before using it with any other fish.

Fin Rot Prevention

The best way to treat Fin Rot is to prevent it from occurring. Here are some helpful tips:

Water & Habitat

Change the water in the tank every one to two weeks and thoroughly clean all decorations, rocks, etc. without using soap. Instead, purchase a cleaner formulated specifically for this purpose from your local pet store or fish dealer.

It is also important to check the pH and the temperature of the water on a regular basis. All fish, particularly those with long flowing fins such as the Betta, have a tendency to contract Fin Rot when the temperature of the water is either too low or too warm for sustained periods of time.


Check that your betta’s food is correct for his specific diet and be extra careful not to overfeed your Betta. It is far better to give your fish smaller quantities of high quality food. Overfeeding will allow excess leftover food to remain in the water, which in turn will increase the concentration of bacteria in your tank.


Be gentle and cautious when handling your Betta. They are easily stressed if they are carelessly handled.

Keeping the habitat controlled, clean and stress free is the best way to ensure your Betta’s health and your continued enjoyment of this beautiful, showy fish.

Is it Fin Rot? Or Fin Loss?

Fin loss

Many people confuse fin rot with fin loss, and the two conditions are significantly different.

As we’ve established, fin rot is a treatable bacterial infection that is often caused by poor water conditions that can leave your betta susceptible to fin rot. Usually, fin rot is identifiable because the edges of your betta’s fins become blackened or bloody, or there is a rapid loss of fin tissue.

This loss of fin tissue can sometimes lead betta owners to confuse fin rot with fin loss. So, what’s the difference?

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Fin loss

Well, the good news is fin loss isn’t a disease. It’s actually physical damage caused by something in the tank, so – thankfully – it’s pretty easy to fix. Symptoms of fin loss include split or torn fins or small, pin-sized holes in the fins.

Because bettas’ fins are so delicate, fin loss is caused by something in the tank, such as:


Bettas’ long, flowing fins can catch and snag on driftwood, bogwood, plastic decorations, plastic plants and sharp rocks.

According to, an easy test can help determine exactly what in the tank is causing the fin loss and damage. Take a pair of women’s nylons and run them over the items and decorations in the tank. If the pantyhose don’t snag, the item is safe for your betta. If the nylons do snag, you should remove the item, or you can often file down sharp edges on rocks and wood.

Plastic plants can’t be filed down and are frequently the main cause of fin loss, which is why many experts recommend using live plants or decorative silk plants.

Bettas’ long, flowing fins can catch and snag on driftwood, bogwood, plastic decorations, plastic plants and sharp rocks.

Fin-nipping fish

The other common culprit is fin-nipping fish, which shouldn’t be added to your tank because bettas can fall prey to the more aggressive fish. Tiger barbs seem to be the biggest bullies, although most schooling barb species, tetras and danios are also known to chase other fish and nip at their fins. If you do have fin-nipping fish in your tank and notice them picking on your bettas, you should remove the bettas or the nipping fish right away.

For more information on betta tankmates and best practices for a community tank, watch this helpful video:

Filter intake

If the filter intake is too strong, it can also cause pulling or snagging of your betta’s fins or can cause their fins to get stuck to or sucked into the intake tube. Make sure you have the proper filter for the size of your tank so the intake isn’t too strong, or turn down the filter flow level.


Identifying the problem as fin loss – rather than fin rot – is the first step to addressing the issue. Once you’ve taken care of the culprits, whether it’s a plastic plant, a piece of bogwood or a bullying fish species, the fin loss should stop and begin to repair itself.

Betta fin tissue usually heals quickly, but keep an eye on their fins to make sure no new tears, splits or holes develop, which could mean you overlooked a problem in the tank. It’s also good to watch the fin damage to be sure no infections develop, which would make treatment more complicated.

Fin rot and fin loss are both common problems with betta fish, but once you know what to look for, you will know how to correctly – and quickly – treat each issue.