Why Is My Betta Fish Looking Fat? (Reasons+Prevention)

Betta fish are known to be hardy fish and can live in a wide range of water conditions, which makes them ideal fish for beginners.

Also, their flawing tails and colourful body attract many owners who love to keep them as pets. However, sometimes you may notice your betta fish changing appearance like they will look fat, which will make you worry. So, Why is my betta fish looking fat? Let us find out.

Overfeeding and low water temperature make your betta fish look fat. The metabolism of your betta fish gets slow in low water temperatures, and they cannot digest their food properly. Provide two to three pellets twice daily, and keep the temperature between 78-82 °F to prevent such issues.

This article will discuss the reasons and prevention for fat betta fish. So, let us get into it.

How to determine if my betta fish is fat or not?

To determine if your betta fish is actually fat or not, observe your betta fish’s body part where their body meets the head.

Your betta fish’s shoulder and head should be the same width.

Betta fish have a celomic cavity where their internal organs are fixed properly.

A celomic cavity is located just behind the head and ends at half or 2/3 on the way down toward the tail.

A betta fish with good body conditions should appear as a torpedo slowly tapering from head to tail.

If your betta fish belly is coming out beyond the size of its head, it is fat.

And if they appear thinner at that part, your betta fish is skinny.

Is it normal for a betta fish to look fat?

It is not normal for a betta fish and every other fish to look fat.

There can be various reasons like overfeeding, inadequate water temperature, illness, and poor feeding behind your betta fish looking fat. However, these are not life-threatening issues but should be treated as soon as possible to prevent your betta fish from suffering.

Overfeeding can cause swim bladder disorder in your betta fish, and inadequate water and temperature can cause stress and various other issues to your betta fish.

So, preventing all these issues will help you make your betta fish happy and ensure their comfortable and long life.

What are the reasons behind my betta fish looking fat?

All these are the reasons behind your betta fish looking fat:

  1. You are overfeeding your betta fish.
  2. The water temperature of your betta fish tank is very low.
  3. Your betta fish is doing a little exercise.
  4. You are feeding high-fat foods to your betta fish.


Overfeeding your betta fish is the primary cause behind your betta fish getting fat.

Bettas have a stomach size similar to their eye, which means that they cannot eat much food at a time.

Feeding them more quantity at a time can also make them suffer from constipation.

When you feed your betta fish more calories than they require, they will become fat.

Also read: How Often To Feed Betta Fish?

Low water temperature

Your betta fish tank’s low water temperature can also be the primary factor behind your betta getting fat.

Low water temperature slows down the metabolism of your betta fish, and your betta fish doesn’t get to digest their food properly. 

Betta fish are tropical freshwater fish that prefer to live in a well-heated tank.

Also, keeping them in a tank with cold water temperature will cause them stress and suffer life-threatening conditions. 

Also read: What Is A Good Water Temperature For Betta Fish?

Lack of exercise

You must know that fishes also have to do some exercise by moving around to prevent them from getting fat.

Betta fish not moving much and staying in one spot most of the time will get fat as all they will do is eat.

Your betta fish need to swim to exercise its body and fins. 

You must provide them ample space to swim all over the tank and stay fit.

Feeding high-fat foods.

If your betta fish is fat, check the foods you are feeding to your betta fish.

If your food contains more fat and less protein, you are feeding the wrong food to them.

Betta fish and every other fish require protein in a major amount.

Food containing more than 10 per cent fat is not ideal for your betta fish.

Also, giving your betta fish treats more than once a week can make them fat.

Avoid providing them with treats like bloodworms, brine shrimp, daphnia, mosquito larvae, and blackworms more than once a week.

Also read: Can Betta Fish Eat Bloodworms?

How to prevent my betta fish from getting fat?

Ensure all these things to prevent your betta fish from getting fat:

  1. Avoid overfeeding your betta fish.
  2. Provide your betta fish with adequate and stable water temperature.
  3. Ensure clean water conditions of your betta fish tank.
  4. Feed your betta fish with high-quality nutritional food.
  5. Provide your betta fish with ample space to live comfortably.

Avoid overfeeding

Feeding your betta fish adequately at a required amount will prevent them from getting fat.

To ensure that you are not overfeeding your betta fish, feed them in a quantity that they can finish eating in one to two minutes.

However, feeding your betta fish two to three pellets twice a day is recommended. 

Feeding more than that can result in overfeeding, and your betta fish will suffer.

Ensure adequate and stable water temperature.

Providing your betta fish with adequate and stable water temperature is necessary to ensure a fast metabolism of your betta fish.

Also, betta fish are tropical freshwater fish and require a well-heated tank to thrive.

Provide your betta fish with a water temperature between 78-82 °F.

Also, add a heater to your betta fish tank to ensure stable water temperature.

Also read: Ideal pH Level For Betta Fish?

Provide clean water conditions.

Keeping your betta fish in clean water will prevent them from various bacteria and parasites, which can affect their abdomen.

Many bacteria and parasites can cause bloating to your betta fish, and they will appear fat.

The main causes of such bacteria and parasites are stress and poor water conditions.

So, to ensure clean water conditions, perform a weekly water change of 35% at least.

Treat the tap water with water conditioner before adding it to your betta tank to dechlorinate it. 

We recommend using the API water conditioner to treat the water, as it will help you eliminate chlorine, chloramine, ammonia, nitrite, and heavy metals from the water.

Also, ensure that betta tank water ammonia and nitrite remain at 0 ppm, whereas nitrate should be below 20 ppm.

We recommend using the API freshwater master test kit to check your fish tank’s ammonia, nitrite, nitrate, and pH level, as it shows an accurate result.

Add a good filtration system to your betta fish tank to prevent water from harmful toxins like ammonia and nitrite.

Consider using a Fluval high-performance aquarium filter for your tank to ensure that your water is clean and protected from harmful toxins like ammonia and nitrite.

Feed high-quality nutritional food.

Bettas are carnivore fish and require meat-based high, protein food in their regular diet.

There are betta pellets available especially for bettas, and you can consider them to feed your bettas.

You can consider feeding your betta fish with Tetra Betta Small Pellets as it is protein-rich and high-quality food.

Also, live, freeze-dried, and frozen food should not be a staple part of your betta fish everyday diet and should be fed as a treat once a week.

Provide ample space

Providing your betta fish with ample space will let them swim around and make them exercise enough to remain fit.

Everybody thinks betta fish can live in a small place as small as 2-3 gallons. 

However, it is incorrect, as betta fish require a large enough space to live and swim comfortably.

A single betta will require a minimum space of 5 gallons to live comfortably.

You should consider providing your betta fish with a large space to ensure comfortable living and a stress-free environment. 

Also read: How Many Betta Fish In a 5-Gallon Tank?


Overfeeding, low water temperature, lack of exercise, and feeding high-fat food are the causes behind your betta fish-looking fat.

Feed your betta fish with 2-3 pellets twice a day, ensure the water temperature is between 78-82 °F, and provide ample space to prevent such issues.

Overfeeding and inadequate water temperature can cause swim bladder disorder, stress, and illness in your betta fish. So, it is necessary to prevent them from such issues.

Reference: ScienceDirect, Scielo, Wikipedia

Recent Posts