5 Reasons Your Betta’s Turning Brown (& What To Do)

Nothing can be more disconcerting than noticing your betta is starting to go brown. However, even if your betta is going brown, it doesn’t necessarily mean you have to worry just yet! In this article, you’re going to find out all the reasons your betta could be turning brown. And more importantly, when it’s due to a problem, what you can do to fix the issue!

So keep reading to find out everything you want to know!

Why Is Your Betta Turning Brown & What To Do About It

Here are all the different reasons that your betta could be turning brown, and when necessary, what you can do to fix the issues!

They’re Aging

One reason that your betta might be turning brown is simply that they’re aging. Just like your hair color begins to fade as you age, your betta’s scales may start to turn brown when they’re aging as well.

On top of going brown, you may also notice that your betta is just fading in general. So if you’ve had your betta for more than a couple of years, then this could be the cause behind them starting to turn brown!

Especially if you haven’t noticed any other symptoms of illness on them, you may just need to accept it’s part of the process of them getting old.

The Marble Gene

The marble gene is a color-changing gene present in some betta fish. The marble gene is co-dominant, so if it’s been bred into the same line your betta came from, then he’s also going to end up with the marble gene.

So if your betta is young and you’ve noticed that they’ve started to go blotchy in some areas, then it could quite possibly be due to the marble gene.

Once again, there’s not a lot you can do to fix this issue. However, fortunately, the marble gene can change the color of your betta more than once. So even if they’re brown at the moment, it’s entirely possible that the blotches will turn into a different color later on in life.

Nitrite Poisoning

Another reason that your betta might be starting to go brown is nitrite poisoning. Unfortunately, when the ammonia in your tank spikes, it’s only a matter of time before the nitrites in your tank spike too!

When this happens, the blood in your betta starts to turn brown, which can be seen on your betta’s body. If left too long, the blood is unable to provide your betta with enough oxygen, so they’ll end up suffocating.

As well as turning brown, you may also notice that your betta starts to gasp at the surface of the water, become lethargic, have rapid gill movement and brown gills, and sometimes stay near water outlets in the tank.

How Do You Treat Nitrite Poisoning?

Fortunately, it’s entirely possible to treat nitrite poisoning, and the earlier you catch it, the greater the chances of recovery for your betta.

The first thing you’ll need to do if your betta is suffering from nitrite poisoning is performing a large water change. Generally speaking, removing about 50% of the water will remove a lot of the nitrate from the tank, instantly improving the conditions your betta is living in.

As well as this, you should also consider decreasing the amount you’re feeding your betta, so not as much waste ends up decaying in the tank, and lastly, increasing aeration, which also helps reduce the amount of nitrite in the tank!

Adding aquarium salt can also be a good way of stopping methemoglobin toxicity, as it can stop nitrite from being absorbed in your bettas’ gills. So if you’re going to add aquarium salt, you should add about 1 tablespoon per gallon of water.

Preventing Nitrite Poisoning In The Future

Fortunately, preventing nitrite poisoning in the future isn’t that hard, and if you follow the steps below, you can make sure that it doesn’t happen to your betta again!

  • Perform regular water changes – The first thing to do is make sure that you’re changing the water regularly. The amount you’ll need to change it depends on the size of the tank and how stocked it is. The bigger the tank and less stocked it is, the more infrequent the water changes will need to be, and vice versa.
  • Don’t feed them too much – You should also make sure that you’re not feeding your betta too much either, and when you’re done feeding them, remove the uneaten food from the tank. This way, you’re going to reduce the amount of decaying waste in the tank.
  • Test the water regularly – And lastly, testing the water regularly will allow you to spot when the ammonia and nitrite are going up in the tank. If you can spot it early enough, then you can prevent nitrite poisoning from happening in the first place.
Male Siamese Fighting Fish isolated white background, Orange Halfmoon Betta Splendens


If you’ve noticed that your betta has been sick for a while and their gills start to turn brown, then they could be suffering from columnaris. However, this isn’t the most common cause, as you’ll spot other symptoms of columnaris before the gills turn brown such as:

  • White cotton-like growths (the most common symptom of columnaris).
  • Frayed fins
  • Ulcers and sores
  • Rubbing against things
  • And in later stages, the mouth will also begin to deteriorate.

How Do You Treat Columnaris?

The treatment of columnaris is actually quite simple; however, the earlier you start treating columnaris, the more likely your betta is to make a full recovery. Here are the steps you’ll need to take to treat columnaris:

  1. First, if you’re keeping your betta with other fish or plants, then you should move them to a quarantine tank so the treatment doesn’t harm them.
  2. Once you’ve done this, you’ll need to start slowly lowering the temperature. At 75°F, columnaris is going to have a much harder time staying alive, and it will also be harder for it to reproduce. Remember not to lower the temperature too fast as this can cause your betta to suffer from temperature shock.
  3. Once the temperature is low enough, you should then start treating your betta with an antibiotic like Furan 2.
  4. You can further lower the amount of stress your betta is feeling by adding aquarium salt to the water as well. (When you’re adding it just make sure you’re using 1 teaspoon per 5 gallons of water.)
  5. With enough time, following these steps, you should notice your betta starting to make a full recovery!

How To Prevent Columnaris

Fortunately, taking basic care of your betta can help prevent them from suffering from columnaris in the first place. So if you want to make sure that your betta doesn’t catch it again, then you should make sure you do the following:

  • Make sure the tank isn’t being cleaned regularly.
  • Don’t overcrowd the tank.
  • Perform water changes regularly.
  • Quarantine any new fish you plan on adding.
  • Make sure your betta isn’t with aggressive fish.
  • And feed your betta a well-balanced diet.

If you do all of the following, then you drastically reduce the chance of your betta catching columnaris!

betta care facebook group

Fin Rot

Last on the list of things that can cause your betta to start turning brown is fin rot! However, if it is fin rot, then your betta will only be turning brown on their fins and tail, not the rest of their body.

As well as turning brown some other symptoms of fin rot include:

  • Fins darkening in color.
  • The tips of the fins may also turn grey or white.
  • They’ll start to look tattered, red, irritated, and sore.

As fin rot progresses and becomes more severe, you may also notice:

  • The fins have receded dangerously close to the body.
  • You may notice that chunks of the fin are starting to fall off.
  • The discoloration may start to turn incredibly bad.

And lastly, if left untreated, you may notice that the fins have rotted right down to the body, and in some cases, even their body will begin to rot as well.

How To Treat Fin Rot In Bettas

Fortunately, if your betta is suffering from fin rot, then it’s actually quite easy to treat, provided that you catch it early enough. So if you’re going to treat your betta for fin rot, here’s what you’ll need to do.

  • First of all, if you’re keeping your betta with any other fish or plants, then you should move them to a quarantine tank so that they aren’t affected.
  • Once you’ve done this, you can also add aquarium salt or API Stress Coat to the tank.
  • As well as this, you should perform a water change in the original tank to improve the water quality.

If they are suffering from major fin rot, then you’ll need to do the following:

  • You should move your betta to a quarantine tank right away; however, this time, you should also remove 100% of the tank’s water.
  • It’s also a good idea to add API Stress Coat again as it can help your betta grow their slime coat back which aids in their growth.

And lastly, in cases of severe fin rot, the treatment is going to need to be more extensive. As well as everything listed above, you’ll also need to use an antibacterial or antifungal such as Furan 2 or API pimafix (depending on what you think is causing the issue).

(Here’s everything you need to know about fin rot in betta.)


As you can see, there are a whole bunch of different things that can be causing your betta to turn brown. However, with the right treatment, you should be able to help your betta and get them back to good health in no time!

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