Hepper is reader-supported. When you buy via links on our site, we may earn an affiliate commission at no cost to you. Learn more.

Why Does My Betta Fish Have A Big Belly? What You Need To Know!

Lindsey Stanton Profile Picture

By Lindsey Stanton

half moon betta fish surfacing

It can be a little odd when you wake up one day to see that your Betta fish is bloated and has a big belly. Bloating, gassiness, and a big belly are not things that you might think your fish can suffer from, but that is not true at all.

Betta fish can and do often have big bellies, unnaturally big bellies which they did not have yet last week. This is most likely a bad sign and it needs to be taken seriously as this could be dropsy. So, why does my Betta fish have a big belly?

divider: bubbles

Overfeeding Your Betta Fish

feeding betta fish
Image Credit: best time photos, Shutterstock

One of the main causes of bloating and oddly big bellies in Betta fish is overfeeding. The reality is that many people overfeed their fish, which is especially true for beginners. Of course, just like with us humans, overfeeding a fish is not a good thing at all. If you feed your Betta fish too much, it will definitely enlarge their bellies, bloat them, and even cause other problems further on down the line.

Overfeeding a Betta fish can result in many different issues. One of these issues is a swim bladder disorder that renders them unable to right themselves in the water. Other serious issues can occur, such as constipation, which is a big cause and a result of bloating at the same time. Constipation comes with its own set of problems that neither you nor your Betta fish wants to have to deal with. Furthermore, Betta fish are carnivores, so if you feed them too many plant-based foods, they will not feel well, get bloated, and most of the food they eat passes through them undigested.

This is a pretty big problem because all of that undigested matter releases a whole lot of ammonia and other unwanted substances into the water. The point here is that feeding your Betta fish too much food is usually what causes bloating and the appearance of a big belly in the majority of situations.

The trick is to feed them no more than they can handle. You should feed your Betta fish twice per day, giving them no more than they can eat in a total of 2 minutes for both eating sessions. You should space the feedings out evenly to be 12 hours apart to give the Betta fish time to digest the food.

Where Is A Betta Fish Stomach?

Remember folks, the Betta fish has a stomach the size of its eyeball, so overfeeding is easily done if you are not paying attention. The betta fish’s stomach is found directly under and behind the head. Just take a look at your betta fish, look at the face, and directly below the face, right under and slightly behind the gills, is where you will find the betta fish stomach.

seashell dividers

Bloating From Dropsy

dropsy in white betta fish
Image Credit: Thassaphong Jarung, Shutterstock

Now, overfeeding your Betta fish, while it can have serious consequences in addition to having an overweight betta fish if you realize what you are doing early enough, is fairly easily fixed and avoided. However, there are more serious causes of why your Betta fish has a big belly.

One of these causes is a very serious condition called Dropsy. Dropsy is not a disease on its own, but a resulting side effect of other conditions. These causes can include overfeeding, a swim bladder disorder, high levels of ammonia and nitrates in the water, as well as parasites and bacteria that have infected your Betta fish. These are all causes of dropsy and they will make your Betta fish’s belly bloat and swell up quite visibly.

Dropsy is the failure of the major organs in your fish. In case you are unsure of whether or not your fish has dropsy, other symptoms include elongated scales, loss of appetite, loss of color, lethargy, sluggishness, clamped fins, pine coning, and a swim bladder disorder.

The big problem here is that once your fish reaches the dropsy stage when fluids are building up internally and organs are failing, it is almost impossible to treat. It can be treated in rare cases, but even so, dropsy and the accompanying organ failure often come back for a second round. If it does not prove fatal the first time around, it will most often be fatal the second time.

aquarium plant divider

Bloated Betta vs. Dropsy: How to Tell?

lavender half moon betta
Image Credit: lmstevendesign, Pixabay

As we have mentioned before, dropsy is not often a result of other conditions or health issues, with bloating being one of the symptoms associated with dropsy.

So, how can you tell if you just have a bloated betta or you have a betta with dropsy? Well, if your betta fish is just bloated, then the bloating will be the only symptom you see, maybe with a bit of sluggishness and a lack of appetite. However, if your betta fish has dropsy, it is going to be bloated, as well as have elongated fins, it will be lethargic, may lose a lot of its color, may have clamped fins, and may also develop a swim bladder disorder.

Your Betta Fish Is Pregnant

betta fish
Image Credit: panpilai paipa, Shutterstock

Another reason why your Betta fish might have a very large belly is that it is a female and she is full of eggs. The first thing you will want to do is to confirm that you indeed have a female Betta fish. The buildup of eggs happens in most female Betta fish when they are preparing to lay eggs and mate with a male.

Of course, the eggs take up a good amount of space, so an enlarged belly is very normal here.

Is My Betta Pregnant or Bloated?

If you have a female, if she has white vertical stripes, and has a little white tube or dot on her belly (where the eggs come out of), you can rest assured that your Betta fish is pregnant.

Now, while this issue is not too serious on its own, you will need to learn how to deal with the Betta fish fry. Some people keep them and take care of them, some people sell the young Betta fish fry for money, and some just let the parents eat the young, as Betta fish are known to do.

starfish divider ah

A Tumor

In very rare cases, a Betta fish may have a big and bloated belly due to a tumor. This does not happen all that often, but it does happen. In other words, the bloating is not bloating, but a tumor visibly bulging. In pretty much every case, unfortunately, tumors in Betta fish will prove to be fatal, either sooner or later.

wave tropical divider


If your Betta fish has a big belly that is enlarged and looks very bloated, it could be due to several different reasons. If you cannot manage to find the cause, and thus the solution, on your own, you should go to a vet and seek medical help for your Betta fish.

While bloating might not seem like a big deal, the reality is that it is often either a cause or a result of a more serious issue that can be disastrous.

Feature Image Credit: at.rma, Shutterstock

Related Articles

Further Reading

Vet Articles

Latest Vet Answers

The latest veterinarians' answers to questions from our database