Betta Fins Curling: 5 Reasons Why and What it Means

One day you wake up and notice your betta’s fins curling up. While your first instinct might be to panic, you shouldn’t until you get all your facts right.

But what are some of the causes? A betta’s fins curling could be due to poor water quality, diseases, or genetic defects. Bettas are proud of their long and beautiful tails and fins, so you’ll definitely notice when they start to curl.

Many betta fish owners have gone through this kind of situation, so your betta fins curling isn’t a new phenomenon.

After carrying out extensive research (which we’ve done for you in this article), you’ll realize there are several reasons why your betta fish fins are curling up, and most of them are normal.

To help you out, this article will give you several reasons why your betta’s fins are curling and what you can do about it. 

5 Reasons Your Betta’s Fins are Curling

Any aquarists will be worried if their betta’s tail or fins start curling up. A betta’s fins are their best trait because they are large and colorful, and bettas think so too. 

While betta fin curling could be a symptom of illness, you shouldn’t jump to conclusions before doing some digging. 

If your Bettas fins are curling, here are some of the common causes and solutions to take care of it:

1. Age

One of the most common reasons betta fins curl up is the betta’s age. These fish only have a 2-4 years lifespan but can live longer with quality care. Normally, their body undergoes several changes as they start to age.

The color on their body starts to fade and their fins may start to curl up as they mature into adults. Their muscle tissue also weakens, which can cause the fin or tail to curl.

betta fins curling

To be sure, you should look for other old-age-related symptoms like:

  • Drowsiness
  • Arched back
  • Frequent naps
  • Lost appetite
  • White patches

If you want more certainty that it’s old age causing the curling of your betta’s fins, check their dorsal fin first. The dorsal fin found at the top will curl, while the bottom fin (ventral fin) will remain hanging as normal. 

If it’s stress or an illness that’s causing it, you’ll notice the ventral fin curling as well.  If old age is the cause of the fin curl, don’t be surprised, it’s very normal for betta fish as they get older.


Unfortunately, you can’t cure old age in any living being. It’s part of the natural cycle, but you can give your betta a great and happy life while they grow old. 

With proper care, these fish can live up to around half a decade or even slightly more. Check out this detailed betta fish care guide for useful tips to keep your betta comfortable and healthy.

If there aren’t any other age-related symptoms, the other reasons on this list could be why your betta’s fins are curling.

2. Illness

Your betta fins curling could be a symptom of illness. Bettas are susceptible to various diseases like fin rot and swim bladder disorder, so you should be prepared when they get sick.

While they are hardy little creatures, their environment plays a key role in their general health. Here are the common diseases that betta fish suffer from:

  • Ich disease
  • Velvet
  • Betta Fin rot
  • Dropsy
  • Swim bladder disease

It’s easy to accidentally introduce a parasite when changing the aquarium plants or adding new fish, so you must be extra careful with bettas. 

When bettas get sick, they won’t be as active in the tank, and you’ll notice more changes in their behavior, like hiding more frequently, laying at the bottom of the tank, or their fins could start curling up.


If your betta is sick, you’ll need to get them medication from a fish store or after a consultation with the vet. You’ll need to quickly identify the illness and symptoms to get adequate treatment for your betta fish. 

Some infections may only require a change in water parameters to treat, but you must be cautious because others are fatal to these Siamese fighting fish.

3. Genetics

Another likely reason your betta’s fins could be curling is a genetic disorder. Some baby bettas are born with curled fins, so you should also expect their fry to be born with them. 

If you suspect this is the case, it would be wise not to breed them with others to avoid passing on the genetics of that particular betta fish to the next generation.

If you see bettas swimming with curled fins, it could be an indicator that they will get more health problems in the future.


Most genetic issues will only be visible after the betta fish has matured. This is around one or two years of age. Just like aging, there isn’t a cure if your betta fish has a genetic issue that makes their fins curl, but that shouldn’t stop you from giving them the love and care they need.  

4. Poor Water Conditions

Bettas are very sensitive freshwater fish, so you must carefully monitor their habitat and water parameters. Their fins can curl if the water temperature is too high, too low, or constantly changing.

Most fishkeepers know that even a slight change in the tank’s temperature can lead to shock and stress for these fish.

For example, the water should have a pH of between 6.5-7.0, temperatures of between 78-82 degrees Fahrenheit, and zero ammonia and nitrite levels to keep these fish healthy.

Poor water conditions stress bettas and expose them to the risk of infections and other diseases like ammonia poisoning.

Water hardness could also be causing your betta’s fins to curl. Hardness refers to the mineral content in the water, which also affects the pH levels. 

These fish will thrive in soft water with a 5-20 DH hardness. Very hard water is not good for your betta fish.


Changing the water regularly will help keep the tank clean and healthy for your betta. Any tank with less than five gallons won’t offer enough swimming space or room for equipment like heaters.

If you want to maintain the perfect water conditions, you should invest in good quality aquarium test kits that will help you test the tank’s PH, ammonia, and nitrate levels. 

The best water for betta fish, recommended by aquarists, is betta-specific water because it meets all the above-mentioned requirements. A good water heater will also help you maintain warm water temperatures.

If your betta fish fins are curling because of water hardness, you can correct it using various products. If you make the necessary changes, you shouldnt worry about their fins curling because they aren’t in pain. It will only affect their appearance.

5. Injuries 

Bettas are you gracious swimmers, but they can still get hurt and damage their fins. If the injury isn’t caused by tank equipment, the problem could be some unfriendly tank mates. If your betta’s fins start curling, they could be scared and trying to protect themselves.

If you thought that bettas don’t have feelings, that’s a myth. Bettas are easily stressed, so the environment has to suit their needs, or they won’t be happy. That includes the other fish that are living within the tank.

If your betta fish is in a community tank, they can quickly get injuries from aggressive fish.  Fish find fins an easy target, and with bettas reputation for fighting, you shouldn’t risk it.


Keeping your betta with other peaceful fish species will keep them more relaxed and prevent fights. Male bettas are territorial, so you should avoid keeping male betta fish together because brightly colored fins threaten them.

Giving your betta more hiding spaces will also help keep them safe and calm. Most injuries betta fish get from fin nipping or fighting will eventually heal. If there are signs of infection, it’s best to seek medication like betta fix or vitamin B treatment.

Other causes of betta fins curling:

  • Exposure to loud noises
  • boredom which can be due to loneliness or lack of decorations in the tank
  • incorrect diet
  • Exposure to harmful chemicals or medication
  • Anything that causes your betta fish stress can cause curling fins. 


What are clamped fins?

Clamped fins are when a fish holds their fins very close to its body. Although clamped fins aren’t a disease, it indicates a more serious problem for your betta fish. A common cause of clamped fins is bullying from other fish, which can cause stress.

How is betta fin curling different from fin rot?

While betta fish fin rot can cause your betta fins to curl, there are other symptoms you should look out for that indicate fin rot, like uneven edges, loss of color, and reddened and inflamed skin at the base of the tail. After treatment, your betta’s fins can regrow. 

Can anxiety cause betta fins to curl? 

Yes. Crinkled fins sometimes indicate tension in bettas. So something in their immediate environment is causing them stress and anxiety. Is it the small tank size, the tank mates, or are they sick?


Bettas fins curling isn’t always normal, so you shouldn’t ignore it if it happens. If it’s not a genetic issue or old age, this could signify something more serious with your betta.

With a little investigation, you will find that the cause could be poor water quality, other aggressive fish, or stress.

The best way to eliminate any serious reasons like illness or poor water quality is to check for other related symptoms. Once you know what’s causing the fin curling, you can help your betta return to its normal behavior.

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