Why is my betta fish getting fat?
It’s an unusual sight as your fish continues to grow larger and larger without letting up.
A betta fish gets fat because it’s eating more than required, has a digestive issue, and/or the water conditions are unstable leading to natural weight gain or bloating.
It’s essential to take action because a fat betta fish will end up having serious health concerns over the long-term. This is why it’s also recommended to speak to a fish-friendly vet that has expertise in assisting betta fish with weight gain.
The benefits include:
- Regulating the Weight
- Adding Nutrients to the Fish’s Diet
- Quicker Changes
Weight gain of any type can be concerning, but it’s essential to pay attention to what the fish is eating throughout the day.
If it has to do with portions and/or the type of fish food your betta is eating, these are simple changes that can be made in a matter of days. Focus on paying attention to your fish and what it needs by understanding the root cause of the fat gain.
This article will answer the question, “Why is my betta fish getting fat?” while also providing detailed tips on what to do when this happens.
Best Fish Food for Betta Fish (EDITOR’S CHOICE)
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Tips on Controlling a Betta Fish’s Weight
Tip #1: Use Low-Calorie Fish Food
If you are asking, “Why is my betta fish getting fat?” then it’s time to start here.
While fish food is essential, this doesn’t mean you give any type to your betta fish. It’s essential to find a verified, well-regarded solution that is low in calories.
There are several benefits of pursuing a low-calorie option for your betta fish.
These benefits include:
- Higher in Nutrients
- Easier on the Digestive System
- Keeps the Weight Gain Down
Once you start using this type of fish food, you are going to notice a subtle change in your betta fish.
This is what you have to aim for as a fish owner when the weight continues to go up.

Tip #2: Reduce the Portions
The portions are often the main reason for a betta fish gaining weight.
This means you should take the time to reduce the portions by a little. To do this, you are going to have to measure the betta’s fish food and make sure it is the same amount every single time.
From this point forward, you can make subtle adjustments downwards.
Remember, this isn’t going to happen overnight.
You will have to stay patient and make regular checks on the portions to ensure they’re consistent. Once you do this, you will easily start seeing a positive change in your betta fish.
Tip #3: Reduce the Water Temperature
When the water temperature is too high, this is going to have a unique effect on your betta fish.
In some cases, the water is way too hot and that can kill your betta fish. However, there is a middle ground where the betta fish is going to start to gain weight due to the conditions, especially if it is well-fed.
This is not a good thing as it is not natural to the betta fish.
You have to regulate the water temperature or the betta fish’s weight is going to spiral out of control.
It’s essential to take regular measurements to see what the temperature is in the fish tank. This is a must and should become a part of your routine every day.

Tip #4: Keep Visual Records of the Betta Fish
Why is my betta fish getting fat?
In general, you shouldn’t have to ask this question when you are keeping track of the fish’s food intake. Unfortunately, it’s difficult to do this and a lot of fish owners don’t have the energy to focus on what the fish is eating.
However, when it’s time to make changes, you are going to need to record each detail.
This means more than just taking out a journal and jotting down the portion sizes! No, you have to start taking pictures/videos to see how the weight gaining is going for your betta fish.
If there are limited improvements in the coming weeks, this means further changes have to be made. A lot of the times, your first adjustment isn’t going to be enough.
Final Thoughts
Why is my betta fish getting fat?
It’s often going to come down to what you are putting in the fish tank. If the wrong type of fish food is given to any fish, it will start to gain weight, especially when the portions are unregulated. You have to be consistent or it is going to have a negative impact on the fish.
The goal should always be to track what you are doing and be willing to make adjustments. This is the only way to keep the pet fish healthy.
If your betta fish has started gaining weight, don’t ignore it!
Start by following the advice written in this guide and then move forward with a plan in hand. It will go a long way in helping your betta fish.
For more on how to assist a betta fish go through these articles – how to impress a betta fish, how to deal with betta fish eating problems, quality HOB filter for betta fish tank, and how to reduce ammonia in a betta fish tank.