Betta Fish Fin Rot

Betta Fish Fin Rot: Causes And Cures

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Fin rot can be scary at first and might send betta fish owners into a state of panic. While ugly and temporarily uncomfortable for your fish, fin rot is very common and luckily, pretty easy to treat.

With early diagnosis and a treatment schedule, your betta fish will most likely recover in no time from fin rot!

Keep reading to find out everything you need to know about betta fish fin rot, how to identify it, and how to cure it in your own freshwater aquarium!

What is fin rot?

sick betta fish with fin rot

Fin rot is caused by bacteria or a fungus. More often than not, you will be dealing with bacteria  (Aeromonas sp., Pseudomonas sp., or Vibrio sp.), but it’s important to know what to look for when diagnosing fin rot in your betta fish.

Fin rot is usually characterized by tattered or deteriorating dorsal, anal, and tail fins, though we will discuss other symptoms later on.

It should be noted that some betta fish might already have fin rot before you take them home from the store. Too often, they are kept in unideal conditions and that shows in their health.

Before buying your betta, check to make sure the fish is breathing and swimming correctly and that all fins are fully intact.

 What causes your betta fish to get fin rot?

The main cause of fin rot is poor water quality. Freshwater aquariums are teeming with life in all forms, all the way down to bacteria that will infect a compromised fish.

For the most part, our fish are able to fight back pathogens, but if the fish becomes stressed, then their immunity is lowered and they become susceptible to the bad bacteria in the tank.

There is no one cause to fin rot, but there are a few things that could have gone wrong in your tank to get you to where you are now.

Imbalanced nutrients

One of the most common causes of fin rot in betta fish is new tank syndrome. This happens when the tank hasn’t been given enough time to properly cycle and there is still unideal water chemistry.

Cycling a tank ensures that when fish are added to the tank, ammonia can be converted to nitrite and then eventually nitrate. Not only this but it also means that your other parameters have stabilized too, including pH and general hardness.

If the tank isn’t given time to properly cycle, then you may be adding your betta into dangerous conditions that could stress out your fish and lead to other complications; ammonia spikes can also be caused by overfeeding, overcrowding, or general poor maintenance.

This will leave your fish with a compromised immune system. On top of that, things like ammonia and nitrite poisoning can cause your fish to spend a lot of time at the bottom of the tank, inviting fin rot to infect your fish.

Water temperature

Similar to imbalanced nutrients, temperature plays a role in the immunity of your fish. Betta fish need a constant 78-80° F (25.6-26.7° C) and cannot tolerate sudden changes in temperature.

Too often, beginner hobbyists don’t know that betta fish need an aquarium heater and need to be kept in warmer tanks. This is mainly due to the fact that they’re sold in tiny cups and it doesn’t look like they need any kind of special aquarium setup.

As a result, betta fish are kept in cold water, overly hot water, or in constantly swinging temperatures. Immunity is compromised in all three situations, lending the fish to fin rot.

Improper tank setup

In addition to tanks lacking heaters, many beginner hobbyists also fail to give their bettas the right home.

The minimum tank size for most bettas is 5 gallons (18.9 L) to allow for enough swimming room and easier control over nutrient levels. Bettas should be kept on sand or fine-grained gravel so that their fins don’t get caught.

Likewise, live plants are the safest for bettas as they don’t rip tail fins, however, the right artificial plant will also keep your betta fish safe.

Some hobbyists try to keep their betta with other fish–which can work given the right setup. If not done correctly though, this can lead to fin-nipping, excess nutrients, and stress for everyone.

How do you know if your betta fish has fin rot?

As mentioned before, there are believed to be two different types of fin rot: bacterial fin rot and fungal fin rot.

Many hobbyists see a fungal infection as a secondary symptom of bacterial fin rot, but it’s important to know how to identify both so that you can start treatment.

Bacterial fin rot

Fin rot can be difficult to catch in the beginning. Usually, the edges of the fins will start to lose their color and become weak. Eventually, this spread inwards to the body of the fish and the fins will fall off with the progression.

This will result in a ragged appearance to mainly the dorsal, anal, and tail fins. During the same time, the fins will look even more discolored and might have red blotchiness or bleeding.

Because your betta is weak, it’s very common for your fish to contract other illnesses or parasites during this time. One of these could be a fungal infection.

Fungal fin rot

Fungal fin rot usually happens once a bacterial fin rot has already taken hold. The ripped fins will become white and can become fuzzy.

At this point, your fish is that much more likely to pick up other infections, like Columnaris or ich.

Preventative measures

Betta fish fin rot can be difficult to identify and diagnose especially on darker-colored fish. It is always a good idea to check on fish daily to make sure they are behaving normally and there aren’t any signs of illness.

Before bringing your betta fish home from the store, check and double-check that your tank is completely cycled. Once you get your fish, give an hour to acclimating your betta with drip acclimation in order to prevent as much stress as possible.

Continue with regular water changes, monitoring temperature, watching any present tank mates, and making sure to not overfeed. Test water regularly to make sure parameters are stable and ideal.

As we’ll discuss later, good water and filtration will be the key to your fish’s recovery.

Daily checklist

For daily checkups, quickly look over the color, fins, and behavior of your fish. Is your fish swimming normally? Is it eating all the food that you put in the tank?

If you see any signs of discoloration or tattered and ragged edges to their fins, then you will want to start treatment for fin rot immediately.

If your betta has already started to show symptoms, how can you know how bad the infection already is?

Stages of betta fish fin rot

Knowing how much fin rot has progressed can help determine which course of treatment will be quickest and most effective for your fish.

Keep in mind that symptoms will not disappear overnight and curing fin rot will take time and effort.

Mild betta fish fin rot

  • Betta fish will have redness and irritation at the tips of the dorsal, anal, and tail fins.
  • Redness and irritation will be localized and only be visible at the edges of the fins.
  • The discoloration at the tips of the fins will appear slightly darker or lighter in color than the rest of the fin.
  • The fin tips will appear only slightly frayed.

Major betta fish fin rot

  • The fins are bloody and possibly covered in fuzz with red blotchiness in many different areas.
  • The fins have started to recede towards the body and are very tattered.
  • The color of the fins is abnormally dark, or even grey, and is it is apparent that those areas are starting to die.
  • This dark coloring extends beyond the fin tips and more towards the base of the fins.
  • There is great damage to the entirety of the fins with large rips, tears, and even chunks missing. It would be clear that this is not damage done by another fish or other injury.

Extreme betta fish fin rot

  • At this stage, the fin rot has transformed into betta fish body rot and the fish needs critical care.
  • The fin rot has actually spread past the fins and onto the body of the betta. The body may start to become discolored and show signs of redness or bleeding.
  • Typically at this point, some fins may have receded completely or there are only pieces hanging from the body.

How to treat fin rot in betta fish

The first step to treating fin rot is remaining calm and organizing a treatment plan; while fin rot might look nasty, even mild and major fin rot stages are still relatively easy to cure.

If your fish is in a tank with others and you have the ability to quarantine that fish, then you should. While fin rot isn’t very contagious, if your water parameters are not good then those other fish are susceptible as well. Also, consider if catching and moving your fish will add more unneeded stress.

If opting to quarantine the affected fish, then a 2.5-5 gallon (9.5-18.9 L) quarantine tank is recommended. This tank should already be cycled or seeded with filter media to create a safe environment for your fish.

Water temperatures should match between the tanks; some sources might say to raise the temperature over time, but this is usually prescribed for parasites and can actually cause more stress to a fish with fin rot.

Next, you will need to decide if you want to use a natural remedy or a chemical medication.

betta fish with fin rot in aquarium

Natural cures and remedies – betta fish fin rot

More often than not, treating fin rot with natural cures and remedies is much easier, more cost-efficient, and less stressful than using medication. However, there is a lot of physical labor and time that needs to be given over the course of a few weeks, and some hobbyists don’t have that.

Here are some ways to help your fish get better without having to use medication.

Water changes and stable parameters

Remember how we said that poor water quality was the leading cause for fin rot? Well, the number one way to treat fin rot is to fix water parameters.

It should be noted that this treatment method is best for fish experiencing mild to light major fin rot. At later stages, you will most likely want to move to more immediate remedies.

While you might be tempted to exchange all the water in your tank for new water all at once, this isn’t a good way to go about treatment. Large shifts in water parameters can stress out your fish even more and lead to bigger problems.

Instead, do small water changes every couple of days. In theory, this eventually replaces all the water in the tank but gives enough time for your fish to adapt to new parameters.

You will want to make sure to do the water change correctly though, to make sure that you don’t stress your fish out even more. New water should be heated to match the exact temperature of the tank and treated with a water conditioner.

It is recommended to do a 20-25% water change every couple of days. For worse cases, you can even bump up that up to every day.

During this time, you will also want to regularly test water parameters to see improvement; keep in mind that a stable tank is much better than perfect parameters.

Aquarium salt

On top of doing more frequent water changes, you can also start to dose aquarium salt; this is not necessary but is encouraged in most cases.

Many hobbyists believe that salt does more harm than good, but it is a good alternative for the most part to other chemical medicines.

Aquarium salt is easy to find and usually pretty inexpensive. It strengthens your fish’s ability to osmoregulate, or the ability for a fish to regulate its bodily fluids in respect to its environment, and overall health.

Many aquarium salts come with directions for use, which should be followed as each brand is different. However, you will want to do water changes in between dosings as too high of a salt concentration can be damaging to your fish.

In addition, prolonged elevated salt levels can also lead to internal and external damage to your fish.

Aquarium salt with live plants

The problem that many hobbyists run into with using aquarium salt is that they have live freshwater plants.

Many freshwater plant species are sensitive to any amount of salt that enters the aquarium; unless you have brackish species, then it is safe to assume that aquarium salt should not be used.

Instead, you can try salt dips; this is much quicker than a salt bath! Keep in mind that this method can be very stressful and should not be used with weaker fish.

A salt dip can be done with one gallon of water heated to the same temperature as the tank water; 1 teaspoon of salt should be added for every gallon. Aquarium salt should never be poured directly into the aquarium and should be mixed in a separate container ahead of time!

Some hobbyists like to do salt dips once a day, while others think once a week keeps the treatment going without overly stressing the fish. Each dip should last 3-5 minutes and abnormal behaviors should be observed.

Other natural remedies

For most fin rot cases, water changes will give your betta a speedy recovery. There are a few ways that you can help your fish get there faster, though.

One of the main ways is to add Indian almond leaves. Betta fish come from tannin-stained waters and Indian almond leaves will do just that while providing a natural boost to their immunity.

Other ways you can guarantee the recovery of your fish are by providing good filtration and good aeration.

Filter floss media should be rinsed with used aquarium water once a week. This will help debris from building up and leaking ammonia back into the tank while providing a porous area for beneficial bacteria. Other filter media should be changed as recommended.

Increased aeration can be achieved with an air pump. This will help introduce more oxygen into the tank and increase gas exchange so that your fish has plenty of air to breathe, which can then be allocated to damaged areas of the body and fins.

One of the important things to keep in mind that stability is key. The temperature should never change for fin rot; while temperature increases might be a popular treatment for other common diseases, like ich, it can actually exacerbate the fungal or bacterial infection.

Medicating – betta fish fin rot

Medication might be scary and there are many products to choose from, but has worked for many hobbyists and can be just as well of a solution to fin rot as natural remedies.

Medications are usually recommended for fish with more extreme fin rot, though are safe to use at any stage.

For the most part, this will involve following the instructions given by the specific product. However, there are a few ways you need to prepare your betta fish for medications.

How to medicate fin rot

1. Remove the fish from the display aquarium if you have live plants and/or other tank mates; some medications can cause plants to become dyed.

Remove carbon from the filter and add an airstone for better oxygenation.

2. Pick a medication. There are many to choose from, and some hobbyists even choose to go with stronger, over-the-counter antibiotics for their betta.

However, some of the most popular aquarium products are Maracyn, Waterlife Myxazin, or Kanaplex.

Some other medications, like Melafix and Bettafix, are commonly recommended for betta fish fin rot as well. However, these products contain oils, like tea tree oil, that can coat the labyrinth organ and make it difficult for your fish to breathe, and can cause permanent damage.

3. Be patient and keep water parameters stable. Recovery can take a while to see depending on the extent of the damage. As long as you see a gradual improvement in your fish, then you are on the right track.

However, if your fish’s health continues to decline over the course of a few weeks, it might be time to look into stronger medications and/or other illnesses.

Signs of recovery

Improvement can be seen in a matter of days with fin rot. Sadly, it will take more than just a few days for your fish to regrow its fins though.

Recovery starts with damage decreasing over time, and it might get worse before it gets better. Eventually, your fish will start to return to its normal color and behavior.

Signs of fin recovery can be a little hard to identify as a regrowing fin actually looks very similar to the beginning stages of fin rot; regrowing fins will have healthy, clear, or white edges that could make you second guess another infection.

There are some big differences between fin regrowth and fin rot, though. Mainly, the new growth will look healthy and uniform. There won’t be any rips and the fins should effortlessly flow.

In order to keep your betta fish on the right track, you will want to decrease water flow, maintain water parameters, and provide a high-quality diet.

While it might be tempting to bring your betta back to the main tank if you have had it in quarantine, remember that there’s no rush and it’s better to allow for full recovery than to have to redo the process in just a few weeks.

Because of this, it’s best to wait 3+ weeks after the first signs of regrowth. While you wait, make sure that the parameters in the display tank are stable and in an appropriate range.


Sadly, betta fins are very susceptible to fin rot and many beginner hobbyists don’t notice symptoms in time or panic and overly-medicate their fish.

Most of the time, fin rot can be treated with a series of water changes, aquarium salt, and overall good water parameters. Medications might be needed for more extreme cases, though the process is relatively easy and straightforward.

Don’t panic! Take it one day at a time and your betta will have flowing fins before long.

If you have any questions about fin rot, betta fish tail types or varieties, or have had experience treating fin rot with your own betta fish, don’t hesitate to leave a comment below!

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