Fat Betta Fish: Why is My Betta Fish SO Fat?


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Has your betta fish gained more weight accompanied by a loss of appetite? 

While it’s not uncommon, betta fish gaining weight could mean a lot of things. It could be that it’s a female fish ready to lay eggs, or perhaps you gave it too much to eat. 

However, fat betta fish may be afflicted with tumors or dropsy, so you need to be vigilant. That’s why, in today’s guide, we will be discussing all the things related to betta fish and weight gain to help you. 

Can Betta Fish Get Fat? 

Betta fish are usually small, so you wouldn’t expect them to be fat. But contrary to popular opinion, betta fish can get fat if they don’t receive the right amount of care. 

There could be several reasons why betta fish may gain weight or look bloated. If you are lucky, it may be a simple case of feeding them too much, which you can easily rectify. 

That said, weight gain often results from diseases like dropsy or tumor, meaning you need to be watchful. 

What Does A Fat Betta Fish Look Like? 

fat betta fish

It is crucial to know what fat betta fish look like so that you can quickly prevent the onset of any disease. Since these are small fish, it’s easy to identify if they look different. 

When viewed from above, betta fish will have a slightly rounded and plump stomach, which may result from overfeeding. But if you are careful, they will return to their original size by the next feeding session. 

However, bulging or abnormally overweight betta fish may be suffering from certain diseases.  

Why Is My Betta Fish Getting Fat Belly? 

So, what are the reasons for a betta fish to gain weight? We have shortlisted some of the most common causes why your betta fish may have put on extra pounds. 


It’s always suggested that given their small size, keeping betta fish on a nutrient-rich diet may lead to weight gain. Similarly, having sufficient fibers in their meals is necessary to keep the fish healthy. 

Foods with a high concentration of nutrients break down quickly and don’t allow enough time for the fish to empty their stomach. This is a common problem, especially if you are a budding aquarist and are unsure about the quantity and variety of a healthy diet. 

Bloating From Dropsy 

Sometimes bloating may result from dropsy, so there are certain tell-tale signs you should know about for easy identification. Dropsy is characterized by elongated fins that look like pine cones. Not to mention, the fish may lose their color and develop clamped fins with a swim bladder disorder. 

There are several causes of the disease, including imperfect water conditions, parasites or bacteria, and overfeeding. If not treated quickly, it may affect the major organs of the fish, leading to its loss of life. 


Unknown to many, betta fish may develop tumors, although it is a rare disorder. You can usually tell by their large and bloated belly, which is out of the ordinary with a visible lump on one side. 

What’s more, asymmetrical bloating may point to the fact that there is an internal tumor. Now, there could be several causes for a tumor, such as poor water conditions, genetic traits, and improper diet. 

The best thing to do would be to consult a vet, as in most cases, tumors are benign.  

Pregnant Female Betta 

If none of the above reasons hold weight, it could be that the female betta fish is pregnant. Naturally, the fish develop a large belly to carry eggs till they are ready to lay the cluster in a suitable spot. 

Given that betta fish can lay between 100 and 150 eggs, it is no surprise that the females develop a big belly. Now, let’s look at how you will determine whether the fish is pregnant or just fat. 

Is My Betta Fish Pregnant Or Fat? 

To solve the mystery, you need to confirm whether it is indeed a female fish and secondly if it’s healthy. One surefire way to identify a pregnant female is if she has white vertical stripes along with a white tube on the underside of her belly. 

In some cases, it’s a dot instead of a tube situated at the point where the eggs will come out. Once you confirm that the female is about to lay eggs, it would be best to plan how to deal with the fry. 


Are Betta Fish Supposed To Be Fat? 

Most people believe that betta fish should be skinny, but the reality is that they can be fat. You need to make sure that you provide them with a healthy diet and maintain the right water conditions so that the fish can thrive. 

That said, if you notice an unnatural change in weight, don’t waste time consulting a vet. Even though they can gain a little weight, their overall body fat should not be more than 5%. 

How Big Is A Betta Fish Stomach? 

The stomach of a betta fish should not be bigger than its eyeballs, and you must feed it a similar amount of food to promote good health. So, to ensure that the fish are well fed without them turning overweight, you need to feed them twice a day, rather than all at once. 


Are you confident that you can take care of betta fish better? 

When owning an aquarium, you need to recreate the natural habitat of the fish as closely as possible. Also, ensure that they are not stressed and prevent sudden changes to the fish tank or its surroundings. 

In case you notice that their belly is bulging for no apparent reason, take action immediately.

That’s it for now, see you soon with another informative guide! 

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Jeff Colt

Jeff Colt

Hello, I'm Jeff- an aquarium enthusiast with over 25 years of experience caring for a wide array of tropical fish, including koi, goldfish bettas, cichlids and more! For me: Aquariums are like jello - there's always room for more!

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