Why Does My Betta Have Clamped Fins?

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Betta fish are beautiful and are known for their large, flowing fins. So when they suffer from clamped fins, Betta fish are telling you that something’s not quite right.

Clamped fins isn’t super uncommon, and it often comes with a bunch of other symptoms in your Betta fish too.

There can be a number of potential causes, so how you treat clamped fins can vary. So let’s take a look at what you should be looking for, and how you can help your Betta fish to feel more relaxed again.

What do clamped fins on a Betta look like?

When healthy, a Betta fish has fins that are widely spread. Clamped fins are when the fins are held tightly close to the fish’s body – it will look a lot more streamlined and narrow than normal, with the fins folded and clumped together.

They won’t always be so tight that the fish looks like an arrow, though. Each fin can still be separate, but the actual fin itself will be tighter together than normal, with the dorsal fin, in particular, leaning back more than normal.

What do a Betta’s clamped fins mean?

There are a number of potential causes of clamped fins with Betta fish. The most common is incorrect water parameters. It can also be a sign of stress caused by the environment or other fish, especially if those tank mates are fin nippers.

With water parameters, you’re looking for the following:

  • Temperature between 75 and 80 degrees Fahrenheit
  • A pH close to 7
  • 0ppm ammonia
  • 0ppm nitrites
  • Less than 20ppm nitrates

Clamped fins can be a result of the water parameters being wrong over time, and causing your fish stress. Or it can be a reaction to a sudden change in the parameters, usually after a water change that’s gone wrong.

Read more: How long does water conditioner take to work?

If the parameters are all correct then look for other signs of stress in your fish. Other reasons that your Betta isn’t opening their fins can be that they don’t feel they’ve got the space to swim freely, or they might not be getting along with their tank mates.

Bullying can sometimes be the cause. Usually Betta fish are the bullies, but if you’ve got one living with larger fish or with ‘fin nippers’ – fish that are known for nibbling on the fins of other fish – then your Betta might be more reclusive and tighten up their fins.

Read more: Can a Betta live with Angelfish?

Betta fish clamped fins treatment

There is no single treatment for clamped fins in Betta fish. You need to identify the cause and rectify that. If the water parameters are wrong, you may need to adjust your heater or do extra water changes. If it’s stress caused by other fish, move your Betta to a separate tank.

Clamped fins is not a condition in Betta fish, it’s a result of the fish being stressed by something else that’s wrong. If you fix the problem that’s causing your fish to worry then they will relax their fins and swim more freely.

If it’s an issue with the temperature of the water, you can either adjust the heater or you can carry out a water change, but don’t add hot or cold water to try to make a big adjustment at once. You should add water that’s a few degrees cooler or warmer at most. Wait a few hours, and then check again.

If it’s an issue with the pH or the levels of ammonia or nitrates, a water change can also help but if the problem seems extreme, you can use additives to either neutralize the water or to remove the unwanted nasties.

For example, to correct a severe spike in ammonia you’ll need a specialist ammonia remover like this one:

However, you’ll need to identify why the water got to that level – check your filter, or consider changing your tank’s plants if necessary.

Read more: Water changes not lowering ammonia? Here’s what to do next

If it seems to be stress caused by other fish, you can either upgrade to a much larger tank and add more hiding places, or just consider separating the fish. Often that’s the best solution when tank mates just aren’t getting along.

You can use the salt bath method, but as the video below explains, this can be risky.

Fish can only be exposed to salt baths for a short period of time – too long, and you risk killing your fish. Not long enough and it won’t be effective. Salt baths should ideally be a last resort.

New Betta with clamped fins? Here’s what you need to know

If you have a new Betta fish with clamped fins, it is likely to be caused by the change in environment and the stress that comes with that. Check that the water is the correct parameters for the Betta to thrive, and then give them some time.

Once they’ve adjusted to their new surroundings, they will likely relax and their fins will revert to normal. Just keep an eye on them, and if they’re still acting stressed after a day or two then you can investigate for a more serious cause – they may have an illness that you weren’t aware of.

What if I have a Betta with clamped fins & no other symptoms?

Clamped fins are often one of the first signs of stress in a fish, so it may be that your Betta is showing the first signs of anxiety if they have clamped fins with no other symptoms.

It would be more likely that your Betta doesn’t have an illness – usually the kinds of illnesses that would cause your fish to be stressed have other visible symptoms, including bloating, discoloration or other fin issues including a rotting effect.

My Betta, Rainbow, on the first day I brought him home

But while you can rule out some illnesses, you’ll still want to investigate why your Betta is feeling stressed.

Why does my Betta fish have clamped fins after a water change?

Betta fish clamping their fins after a water change would be a likely sign of temperature shock. Even water that’s just a few degrees different can cause your fish to feel stress as it takes time for the water temperature to normalize across the whole tank.

The best way to avoid temperature shock is to do a water change when the water is as close to the tank temperature as possible. You can heat the new water before a change, and then wait for the temperature to come down so that it matches the water in the tank.

I avoid using hot tap water to balance out the temperature. This is because heating systems often carry chemicals that are harmful to fish. Instead, I rely on boiled water only to bring the overall temperature up to match that of my Betta’s tank.

Make sure that you’re using a thermometer to check the temperature in the tank, and not just relying on the heater’s settings, since the heater could be inaccurate. Use the same thermometer to check the tank water and the new water, and when they’re the same you can carry out the water change.

Read more: Betta Temperature Shock Symptoms

How To Regulate Tank Temperature

There are some great aquarium heaters available from pet stores and online, but there is a product that many fish owners are turning to that is something of a game-changer.

Inkbird ITC-306A WiFi Temperature Controller

  • Protects fish from overheated water
  • Dual display window; displays measured and set temperature at same time
  • High and low temperature alarms
  • Heating time can be set from 1-72 hours if needed

It’s difficult to avoid temperature swings that can be harmful to fish, especially when your room experiences high temperatures in summer or the temperature drops in winter.

Unlike regular tank heaters, the Inkbird allows you to keep on top of your water temperature with a number of unique features.

You can pair the aquarium temperature controller with your phone via 2.4GHz Wi-Fi the INKBIRD app will alert you with push notifications if it senses a problem.

The aquarium temperature controller is equipped with 2 relays to ensure that the power can be turned off under any circumstances, this will protect your fish from being hurt by overheated water (US Socket Only).

The controller uses two probes, in case one stops working. The dual probe aquarium temperature controller will alarm if the temperature difference between 2 probes is bigger than 3°C/5°F, and the INKBIRD app will send a push notification to your phone to alert you.

The heating time can be set according to your needs from 1 hour to 72 hours, and the controller will alarm if water can not be heated to the setting temperature within the specified time.

The 1100w high-power aquarium temperature controller is compatible with most kinds of heaters, so you don’t need to assemble the product yourself, just plug and play.

If you want complete peace of mind, this product takes total care of your water temperature.


The biggest thing you can take away from this is that clamped fins are not a standalone condition for Betta fish, and they are a reaction to another problem. You aren’t trying to fix clamped fins, but you’re trying to work out what’s caused your Betta to react in this way, and then you can correct that.

You should be monitoring your Betta’s water on a regular basis anyway, and just make sure you’re careful with any water changes. Once you’ve ruled out water problems, it should be relatively easy to identify whether your Betta is stressed by their environment, or failing that if there’s an illness you need to investigate.

Hopefully, you find the problem and fix it quickly, so your Betta can return to enjoying a healthy and happy lifestyle.

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