Curled and Clamped Betta Fins: Causes & Treatment

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As a betta fish admirer, I got a little disturbed when I saw its fins becoming curled and clamped. My first assumption was that fin rot is the underlying cause. However, as I researched the topic more extensively, I figured that curling and clamped betta fins could result from different reasons and that the treatment varies accordingly.

Betta fins curling occurs most frequently as a result of old age and genetic defects. However, that could also be due to injury or inadequate water parameters, including pH, ammonia, nitrates, and water hardness. These conditions, along with infections, may also turn the betta’s fins clamped.

As we move forward, I will share a few techniques to treat curling and clamped fins among betta fish. Also, I will show you how to recognize fin rot disease among bettas, and how to treat it properly (followed by a detailed video).

Also Read: Betta Fish Diseases

Curled Betta Fins: Causes and Treatment

The state of your betta’s fins speaks volumes about its health. Whenever you go betta shopping, you are encouraged to prioritize fish with straight, unblemished fins. That is because curled ones are a sign of trouble.

When a betta’s fins curl, some people immediately assume that fin rot is to blame. But this is rarely the case. First of all, curled fins are usually a symptom of a problem. They are not, on their own, a problem. Plenty of aquarists will tell you that their fish have curled fins, but they are happy and healthy.

Naturally, this isn’t always the case. However, it is essential to understand that curled fins are a symptom because this compels you to search for the root cause behind this occurrence. Curled fins in bettas have numerous potential causes, including:

1. Age-Related

Bettas have a lifespan of 2-4 years, though proper care can extend that figure to 10 years. However, regardless of how well you treat them, all bettas eventually wear out with age. One symptom of growing old is the curling of fins at their ends. Fins in aging bettas will also fray and twist. 

You can’t do anything to slow or reverse this process. If you have been growing your betta for many years, curling fins are merely a natural occurrence. Besides that, old bettas present additional features, such as faded colors, sleepiness, and white spots.[1]

2. Genetics

Curling in some bettas is the result of a genetic anomaly. Like the aging factor, you cannot correct a genetic anomaly in bettas. If your bettas were born with curled fins, the fry they eventually produce would manifest this same abnormality. Your only option in such cases is to eliminate the betta fish in question.

If you suspect that this is your case, you should avoid breeding that particular betta fish. The next generation is likely to have the same issue. Also, you should avoid purchasing young bettas that have been swimming with curled ancestors. These are more likely to develop symptoms in the future. 

3. Injury

Bettas have an aggressive streak. They are highly territorial, especially the males.[2] As such, injuries in betta tanks are nothing new. The fins are an easy target. Some bettas will even attack their own fins. 

When a betta’s fins are injured, there is no guarantee that they will return to their original state once they heal. If your fish is perfectly healthy and the water conditions are satisfactory, you can probably blame any curled fins you observe on injuries.

Nevertheless, some injuries will resolve on their own. That is why the treatment, in this case, is mainly by prevention. Make sure you eliminate all potential causes for the bruise. If your betta shares the same tank with another fish, consider separating the two. You should also remove sharps objects and decorations in case your tank features any.

4. Water Hardness

The term ‘hardness’ is concerned with the volume of minerals in the water. Water hardness is associated directly with pH. The harder the water, the higher the level of dissolved minerals, and the higher the pH (and vise versa).

Every fish species has a particular hardness that it can tolerate. For instance, bettas thrive in water whose hardness ranges from 5 to 20 dH. If the water is too hard, it can cause the fins of your bettas to curl. Fortunately, if that is the case, the issue is reversible.

Many regions utilize water systems that make use of water softeners. As such, water hardness is rarely a factor. However, if you encounter this issue in your aquarium, you can resolve it by using sera super peat or any other water softener that piques your interest.[3]

To determine whether your water is soft or hard, check the Youtube video above. It offers some helpful techniques on how to make a DIY testing kit without spending too much money. If your water is too hard, there are cheap solutions (less than $10). One great choice would be the API Aquarium Filtration Media (link to Amazon).

It should be noted that fins that curl as a result of water hardness are not necessarily a cause for concern. The betta isn’t in pain, and the main concerns here are esthetics. That should be noted because water hardness is a tricky issue. 

In trying to correct it, you could dramatically change the pH, making the situation in your tank so much worse. If you doubt your ability to change the hardness without affecting the pH, you are better off leaving this issue alone. That is especially if curled fins in bettas don’t bother you.

5. Water Parameters

The hardness of water isn’t your only source of concern where a betta fish tank is concerned. You have to keep an eye on the other parameters as well. For instance, you need a temperature of 76 to 81 degrees F, a pH ranging from 6.5 to 7.5, and zero ammonia.[4] 

The nitrate concentration has to be less than 40 ppm, and the nitrite levels should be zero. Like the hardness, the wrong pH can cause your betta’s fins to curl. You can expect similar results from a tank with high levels of nitrate. Nitrate isn’t as dangerous as ammonia or nitrites, but it can still cause problematic side effects such as bent spines and spastic swimming, not to mention curling.[5]

As has been noted, nitrites and ammonia are highly poisonous to fish. Fin curling is just one symptom among many that will begin to manifest once the concentration of these toxins spikes. Ultimately, your betta may get sick and even dead.

One effective solution is to carry out regular water changes (10-15% weekly water changes will suffice in most cases). To make sure that this is enough, test your water regularly. From my experience, the API Reef Master Test Kit (link to Amazon) is the cheapest and most straightforward choice.

With ammonia, a water cycle is also necessary. You should also eliminate any components in the tank that contribute to the elevation of ammonia levels, such as rotting leftovers and dead plants.

You have to keep an eye on the parameters in your tank to prevent conditions from deteriorating to a point where your betta’s fins begin to curl. Test the water weekly to ensure that all the parameters are within the appropriate range.

6. Stress

Keep an eye out for factors that might cause stress. Stress can attract a wide variety of symptoms in fish, including curled fins. One of the most common causes of stress in betta fish is small tanks. You should also Look at the bettas that come out of local stores. A lot of them have deformed fins because they are kept in tiny containers.

If your betta tank is less than five gallons, you probably need to upgrade. If the tank size isn’t to blame, consider the diet. See to it that your bettas eat plenty of protein-rich food. You should also keep larger, aggressive fish away from them, not to mention adding plants that can provide hiding places.

Clamped Betta Fins: Causes and Treatment

Like curled fins, clamped fins are not an illness. They are a sign of various problems. If your betta’s fins are folded against its body, the solution you will use to resolve it will depend on the cause. For instance:

1. Ich Disease & Infections

Fish that have ich will develop spots that look like salt all over their bodies. Besides clamping, other symptoms include rapid breathing and glancing. Common causes of ich include stress, rapid temperature changes, and variations in the pH. You can treat ich using antibiotics and drugs like ‘Lifeguard’ and ‘Fungus Guard.[6]

If the clamping is the result of an infection, you can add aquarium salt (one tablespoon per gallon) to the tank.[7] You should use the salt in tandem with antibiotics. Consider talking to a vet to get recommendations.

Also Read: Betta Fish Rubbing

2. Bullying

Stress is a common cause of clamped fins in fish, and bullying is a common cause of stress in fish. If your betta shares its tank with aggressive fish, move the betta to a different aquarium. Preferably, choose the larger one for the betta fish and the smaller tank for the attacker.

If this isn’t an option, give your bettas new hiding places by introducing plants and decorative items to the tank.  That will give the bettas a reprieve from the bullying.[8] If this were the primary source of clamping in your bettas, the issue would resolve itself once you remove the bullying source.

3. Water Conditions

Poor water conditions can cause clamping in bettas. Like most fish, bettas require particular conditions to thrive in a tank. You have to provide and maintain these conditions to keep the bettas healthy. If your betta’s fins are clamped, test the water. 

Ensure that the pH, temperature, hardness, nitrate, nitrite, and ammonia levels are within the relevant ranges. To bring some relief to your bettas, you are also encouraged to carry out water changes. Start with a 50 percent water change and then follow this up with 10-25% water changes.[9] Do this every day until your betta’s health improves.

4. Food

You have to ensure that your betta is adequately fed. If the clamped fins are the consequence of a disease, don’t stop at sprinkling food on the tank’s surface. Observe the water to ensure that your betta is actually eating. Some diseases induce lethargy in bettas, making them so inactive that they stop eating altogether. 

If you notice such behavior, use a turkey baster to squirt the food at its face to get some into its mouth. If you start noticing large quantities of leftovers in the tank, your betta is probably not eating. This will make its condition much worse.

What Does Betta Fin Rot Look Like?

Fin rot is a disease caused by bacteria or fungal pathogens.[10] It can be blamed on poor conditions in the tank, crowding, and stress, to mention but a few. Anything that weakens the immune system can pave the way for fin rot to take root.

These are the typical signs for a fin rot in betta fish:

  1. The edges of the fins (or tail) will fray.
  2. In mild cases, the edges will manifest white spots with brown or black tips.
  3. In moderate cases, the fins will turn black, and you will see white patches at the edges, possibly even hair (or fuzzy growths).
  4. In severe cases, the fins’ state will deteriorate drastically to a point where the fins will fall off altogether. You will observe a red tinge all over the betta’s body.

Besides the physical side effects,[11] the betta’s appetite will wane, and it will become lethargic. It might spend most of its time lying at the bottom, inactive. That condition is different than clamped or curled fins and requires immediate treatment. Follow the video above to get a better idea of how to deal with it.


A betta fish’s fins may appear curled and clamped due to environmental factors such as stress and inappropriate water conditions. To solve that issue, you have to ensure that the parameters (pH, ammonia, nitrates, etc.) are within the desired range.

You should also eliminate stress, such as a bullying companion or a too narrow tank. Lastly, make sure not to confuse the condition with fin rot, which requires a different approach. With that disease, the fins appear worn and in different colors (such as black, white, and brown).