The Fat Betta Fish Guide

If you have looked in your tank and realized you are now the proud keeper of a fat Betta fish, usually it means one of four things…

Poor Diet

A lot can go wrong when it comes to feeding a Betta fish. Too large of servings, too frequent of servings, feeding the wrong foods, not properly preparing the foods before feeding – these are all things that can causes the abdomen of your Betta fish to enlarge. To avoid any issues, read our guide: How To Feed A Betta The Best Betta Food.


The term “Dropsy” refers to a condition where a fish’s abdomen fills with fluid and, after time, it’s scales stand up on end – giving it a pine cone-like appearance.

The cause of Dropsy is hard to determine because it is associated with so many different things. Infections, tumors, improper water conditions, improper tank mates – all of these things can cause your Betta fish to acquire the Dropsy condition and the “fat Betta fish” nickname.

If you think your fish may have dropsy, check out our dropsy treatment page.


When a female Betta fish is carrying eggs, her underbelly will enlarge. Don’t worry, it’s completely natural. If this is the case, after a few days, she’ll either spawn the eggs or her body will reabsorb their nutrients.

Cancerous Tumor

Just like humans, Betta fish develop tumors and cancer cells too. Some of these tumors or cancer cells can grow and enlarge the size of a Betta’s body. Fortunately, some tumors and cancers are treatable, but many are not. For information on diagnoses and treatment, it’s best to contact a veterinarian.

If you have a fat betta fish and it’s none of the things listed above, it’s probably best if you contact a veterinarian for more information.