Skip to Content

Crowntail Betta Fin Rot: Causes, Treatment, and Misdiagnosis

Crowntail Betta Fin Rot: Causes, Treatment, and Misdiagnosis

No one likes having their fish sick! This especially goes for illnesses that can kill them and ruin their good looks. This is why crowntail betta fin rot is so tragic. It can destroy not just the lives of our fish, but also their gorgeous, crown-like tails. 

Diagnosing fin rot can be challenging, especially on fish with spiky tales such as crowntail bettas. This disease can go unnoticed for a while until it reaches its final stages. 

Not to mention how it can be confused with many other causes of ruined tails on crowntails! 

So, what exactly is fin rot, is it treatable, and how can you be sure that this is the condition you and your crowntail are dealing with? Here is everything you need to know!

What Is Fin Rot?

what is fin rot chart table

Fin rot is a group of diseases that affects fish fins. While all fins can be equally affected, the damage on the caudal fin is usually the first thing fish keepers notice.

Despite what many people think, fin rot isn’t a single disease. Rather, it’s a symptom of many different illnesses and conditions. This is what makes treatment rather tricky.

While fin rot can be found in nature, it’s more common in aquariums. This is likely caused due to lower water fluctuation and improper water quality.


No matter the cause of the fin rot, the symptoms will almost always be the same. 

This disease will attack the edge of the fish fins, spreading towards the base of the fins until it has  reached the fish’s body. 

Some of the most common and severe symptoms of fin rot include:

  • The appearance of holes on the fish fins and tail.
  • The edges of the fins have turned black. 
  • Pieces of the fins are falling off. 
  • White dots on the fins.
  • Blood on the fins.
  • Cottony growths on the fins and body.
  • Lethargy.
  • Swimming issues.

Most of these can be challenging to detect on a crowntail betta due to the unique shape of its fins. This is why most fish keepers don’t realize their crowntail is sick until the disease has advanced.


Fin rot can be divided into three categories depending on its cause:

The biggest clue as to whether your crowntail betta has a bacterial or fungal fin rot is the discoloration on the tail. Fungal fin rot will usually lead to fuzzy growth and white spots, while bacterial fin rot typically leads to black edges. 

However, bacterial and fungal fin rot can sometimes appear together, and this is called combined fin rot. 

The main cause of fin rot is stress and improper living environments. Such things will lead to weakened immunity, and your fish might develop fin rot, as well as numerous other conditions.


Crowntail betta fin rot can develop into three stages, each with more complications than the one before it. 

It’s important to be wary of the early signs of the disease. The more fin rot has progressed, the more severe the impact the disease will have on your crowntail. This can greatly affect the chances of recovery. 

Mild Fin Rot

This is the first stage and the one that is easiest to treat. 

During this time, the disease has just infected your fish and the first symptoms have become visible

Mild fin rot is characterized by the discoloration of the fins (usually, you can see the tips of your crowntail betta’s fins have become black or brown, and it’s possible to see some white spots). 

Unfortunately, these discolorations might go unnoticed on some crowntail betta colors, especially on black orchid or marble fish.

It is at this time that your betta’s fins might start to appear jagged or torn, but there shouldn’t be any major changes to the appearance of the tail. 

Moderate Fin Rot

When the disease progresses to the second stage, the fin reductions will become more visible. It’s possible for your crowntail to lose large chunks of its tail and for its fins to become entirely black. 

Also, you might start seeing white patches and cotton-like growth on your crowntail fins, but this doesn’t have to happen, especially if the disease is bacterial. I’ve seen severe cases of fin rot without any fuzzy growths. 

Severe Fin Rot

This is the final stage, and it can be challenging to fully recover a crowntail with a severe case of fin rot. 

During this stage, most if not all of the fins have deteriorated. The disease has started to spread on the fish’s body, which can lead to symptoms such as body discoloration or lethargy.

If a crowntail has lost all of its tail, it will never grow back

Also, as the betta has lost such a significant part of its fins, it will no longer be able to swim properly. This can lead to significant behavior changes and difficulties swimming.

In the most severe cases, fin rot might lead to columnaris. This is when the tissue damage spreads from fins to the fish’s body. 

Unfortunately, your crowntail betta might die if you don’t provide it with urgent treatment. Even if it survives, there are great chances of permanent damage.


Luckily for all of us – and for our fish – fin rot is treatable. While it can lead to death, this only occurs if you’ve left it untreated for a long while.

Of course, before you’ve started giving your fish any treatment, it’s essential to quarantine your crowntail betta fish if they happen to be living with tank mates. This will prevent the disease from spreading.

The exact treatment will depend on the severity of the disease. Here are some of the things that might help:

Water Change

Fin rot is usually caused by improper water conditions, such as wrong pH levels, hard water, or lack of oxygen. 

If you change the water and make sure you’ve picked the right conditions this time, chances are your fish will recover on its own.

You don’t need to change the entirety of the water, unless the conditions are too bad. Changing around 50% of the water will do the job

You can keep your betta fish inside the tank while you change the water and clean the tank. This will save your fish from any additional stress.

Aquarium Salt

Aquarium salt has both antifungal and antibacterial properties, making it one of the most effective treatment methods for fin rot. 

Add one tablespoon of aquarium salt per 5 gallons of water. This amount won’t hurt the fish, but it will help with the disease. You should see the progress in a matter of days!

Just keep in mind that aquarium salt might kill any snails that are keeping your crowntail betta fish company! Always make sure that you have quarantined your betta before adding salt.

Indian Almond Leaves

Not many people know this, but you can also treat fin rot with Indian almond leaves or Indian almond leaf extract!

Indian almond leaves are full of tannins and various other antiseptic chemicals. This gives them antifungal and ant-bacterial properties, making them a perfect choice for treating fungal rot!

A word of caution: I’ve tried this treatment on my betta fish, and betta fish only. Some fish species are highly sensitive to tannins. While crowntail bettas are not one of them, I would still advise you to do the proper research beforehand.

Also, tannins might lower the pH levels inside the tank. Make sure you know some methods for raising pH levels if the water parameters change too much. 


Finally, the only way to treat severe cases of fin rot in bettas is to give them antibiotics or other medications. This includes malachite green methylene, phenoxyethanol, or antibiotic injections.

Most of these can be found at a local pet store, or you can even consult a veterinarian about getting them.

Other Causes of Fin Loss

Fin rot isn’t the only cause of ruined tails in crowntail bettas. Your betta might have damaged fins out of several more reasons, such as:

  • Fin nipping
  • Sharp decorations
  • Rough substrate

Many novice fish keepers believe their betta has sustained some type of physical damage to their fins, which is why their tails are jagged. This is why many cases of fin rot end up undetected. 

There is one clear indication that your fish has fin rot and not some other conditions, and that is the black edges of the fins. If your crowntail betta has been in a fight, its tail might be ruined, but there won’t be any discolorations. 

Always look for tiny details when examining your crowntail.

Final Words

Fin rot is probably the most common disease that can affect your crowntail bettas. It is also one of the most tragic ones, as nothing is worse than seeing a glorious crowntail losing its magnificent tail. 

Fortunately, there are many things you can do to save your crowntail, provided you’ve diagnosed the disease on time. Unless the tail has been entirely lost, it will grow back over time, and your betta can return to its full glory.

Early detection is the key, so be sure you’re always keeping a close eye on your beauty.