Betta Fish Fin Rot

Betta Fish Fin Rot: Heal Your Pet With Pro Tips

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At Bettasource, we’ve written countless articles about betta fish health issues, but few show up as frequently as fin rot.

Fin rot is one of the most common diseases in betta fish, caused by bacterial or fungal infections. Luckily, it is fairly easy to treat so long as you catch it early enough. Here we’ll show you how.

Key Takeaways

  • Fin rot is one of the most common diseases to affect betta fish. It’s an umbrella term for infections that cause fins to become ragged and frayed.
  • Eminently treatable, most betta fish can make a full recovery from fin rot when provided with high water quality and natural remedies.
  • Only in serious cases are medications recommended. The key to success is to remain calm and follow a consistent treatment plan.

Firstly, 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.

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, healthy fish can fight off pathogens, but when stressed, fish become stressed, and then their immunity is lowered.

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.

Fin Rot Starting in an Aquarium Store

It should be noted that some betta fish might already have fin rot before you take them home from the store.

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

New Tank Syndrome

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 unstable water chemistry.

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

Stable water 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 temperature changes.

Without a reliable aquarium heater, immunity is compromised, lending the fish to fin rot.

Improper Tank Setup

The minimum tank size for 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 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 treat them effectively.

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 spreads inwards to the body of the fish and the fins will fall off with the progression.

This will result in a ragged appearance mainly in the dorsal, anal, and tail fins. During the same time, the fins will look even more discolored and might have red blotches or show 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 often fuzzy.

Further infections, like Columnaris or ich, may also set in. Preventative measures

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 acclimate your betta with drip acclimation 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.

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

  • Slightly ragged or frayed edges to dorsal, anal, and tail fins.
  • Redness and irritation may also be localized and 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.

Major Betta Fish Fin Rot

  • The fins are bloody and possibly covered in fuzz with red blotches in many places.
  • The fins have started to recede towards the body and are very tattered.
  • The color of the fins is abnormally dark, or even gray, and it is apparent that those areas are dying back.

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 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.

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 major fin rot stages can still usually be cured.

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 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.

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 a few weeks.

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

Water Changes and Stable Parameters

Since poor water quality is the leading cause of fin rot, the number one way to treat it is to improve tank conditions.

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.

Instead of large water changes, do small 20-25% water changes every couple of days, or every day in severe cases. This eventually replaces all the water in the tank but gives enough time for your fish to adapt to new parameters.

New water should be heated to match the exact temperature of the tank and treated with a water conditioner. During this time, test water parameters regularly to monitor 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 always necessary but is encouraged in more serious cases.

Aquarium salt is easy to find and inexpensive. It strengthens your fish’s ability to osmoregulate, or the ability of 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 dosing 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 improve chances of full recovery are by providing good filtration and aeration. The cleaner water and additional oxygen will provide a good environment for healing.

Filter floss media should be rinsed with used aquarium water regularly to improve performance. Increased aeration can be also achieved with an air pump.

Medicating Betta Fish Fin Rot

betta fish with fin rot in aquarium

Personally, I’d advise staying away from medications unless symptoms are extreme. Meds may have side effects on both your betta fish and its tank mates and also can lead to imbalances in the tank’s biochemistry.

Using medications involves following the instructions given by the specific product. However, there are a few broad principles that you’ll usually need to follow:

How to Medicate Fin Rot

  • 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.

  • 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, and 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, make it difficult for your fish to breathe, and can cause permanent damage.

  • 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 next few weeks, it might be time to look into stronger medications and/or diagnose 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 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.

When To Reintroduce Your Betta to the Main Tank

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 beginners don’t notice symptoms in time or panic and over-medicate their fish.

Most of the time, fin rot can be treated with a series of water changes, aquarium salt, and overall good aquarium maintenance. Medications are usually only needed in extreme cases.

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