Is my betta fish underweight?

In this blog, we will learn about underweight betta fish. We also focus on how to care for underweight betta fish.


In this blog

  • Is my betta fish underweight?
  • How can you tell if your betta fish is underweight?
  • How do you care for an underweight betta fish?
  • What is more injurious -overfeeding or underfeeding a betta fish?
  • How can you tell if your betta fish is recovering from being underweight?
  • Summary 
  • Frequently asked questions
  • Reference

Is my betta fish underweight?

Betta fish are known as greedy eaters and can eat as many times as you feed them. Feeding your fish is important, but making sure you feed them the right thing is also important. 

Some betta keepers feed their betta fish like there is no tomorrow and some due to their busy routines forget to feed their fish sometimes.

If you feed your betta fish too much, they may become overweight and more likely to have digestive issues. If you don’t feed them properly or give them food of poor quality, they may become underweight.

An underweight betta fish will look weak, skinny and colourless.We will discuss in detail an underweight betta fish and will also figure out how we can help bettas to regain their normal weight.

How can you tell if your betta fish is underweight?

If you monitor or interact with your betta fish regularly you can easily make out if your fish is overweight or underweight and can take steps to take care of your fish depending upon the situation. A responsible betta keeper will not leave any stone unturned to keep their fish happy, healthy, and stress-free.

To determine if your betta fish is underweight, you need to pay close attention to them:

  • Betta fish will look skinny and bony.
  • Betta fish will start losing their color.
  • They will become concave-shaped.
  • Tails will become thin.
  • Betta fish will clamp their pectoral fins.
  • Betta fish will become feeble due to a lack of energy in their body.
  • They will stop swimming, as it requires a lot of energy to drag those pectoral fins.

How do you care for an underweight betta fish?

The weight of a healthy betta fish is between 2-4 grams and anything below two is considered as underweight and above four is considered as overweight.

Despite being a bit difficult, caring for a betta fish is not impossible. If you love your fish, you will take good care of them, no matter what they demand. Demand doesn’t mean your fish will say do this for me do that for me, they will signal what is making them uncomfortable in the tank.

If you observe or monitor them regularly you will understand the do’s and don’ts for your fish. If you want your skinny or underweight to regain their normal weight then do the following:

  • Consult your vet about betta fish weight
  • Feed proteinaceous diet to your underweight betta fish
  • Feed betta-specific pellets to your underweight betta fish

Consult your vet about betta fish weight

The first and the foremost thing you do as a betta keeper is to consult a vet. Your vet will examine the fish and tell the solution accordingly. If he/she says to go ahead with a protein diet then you can start feeding them live and other frozen food.

If your fish doesn’t regain its normal weight then you need to consult with your vet again to diagnose the issue. 

Feed proteinaceous diet to your underweight betta fish

Protein source for betta fish comes from feeding them lots of live food. They relish eating live food, especially insects and worms. You can feed your underweight betta fish insects as it contains proteins.

  • Freeze-dried mosquito larvae
  • Freeze-dried bloodworms
  • Brines shrimps or artemia salina 
  • Daphnia or water fleas
  • Tubifex worms
  • Mealworms 
  • Fairy shrimps

Always quarantine live food before feeding your bettas fish,because they are already skinny and feeble and if they happen to eat infectious live food they might get susceptible to various parasitic infections.

If live food is not available then you can feed the freeze-dried or frozen live food, as you don’t have to quarantine these food and wait for weeks before feeding your fish. You can directly get it from pet shops and keep it in the freezer. 

Make sure you defrost, freeze-dried or frozen food before feeding your betta fish. It is important to thaw frozen food, so don’t forget to do this.

It is recommended to feed live food and frozen food once or twice a week to betta fish. Feeding it daily can cause digestive issues, so feed them live food as a treat along with various other foods.

Feed betta-specific pellets to your underweight betta fish

There are betta-specific pellets specially designed for betta fish as it is made considering the amount of proteins and other nutrients required for betta fish.

It is recommended to feed two to four betta-specific pellets to your betta fish twice a day. You start giving with two pellets then gradually increase to four pellets per day twice a day.

Don’t feed low-quality pellets to your betta fish, as low-quality pellets will not provide the required nutrition to your betta fish and will keep your betta fish skinny and unhealthy.

Commercial pellets especially designed for bettas are available online as well as offline, you can choose as per your betta fish requirement. I will list out few betta-specific pellets below:

  • Hikari betta pellets 
  • New spectrum betta pellets
  • Aqueon betta pellets.
  • Ocean nutrition betta pellets
  • Tetra Betta mini pellets 

What is more injurious- overfeeding or underfeeding a betta fish?

In my opinion, neither overfeeding your betta fish is healthy nor underfeeding them. Both have various downsides:

Overfeeding disadvantages:

  • Overfeeding your betta fish can increase their weight above four grams, which is not normal.
  • An overweight betta becomes lethargic and prefers to stay in one place.
  • Overfeeding leads to various digestive issues like constipation, swim bladder disease, and many more.
  • Disorders due to overfeeding issues are not curable. If it is detected early, then it is possible to reverse the situation.

 Underfeeding disadvantages:

  • Underfeeding your betta fish can reduce their weight below two grams, which is not normal.
  • An underweight betta fish becomes feeble and lacks the energy to move. They will move slowly, as it takes lots of energy to drag those massive fins.
  • Underfeeding makes betta fish weak and a weak fish is susceptible to various unwanted infections in the tank.
  • Disorders due to overfeeding issues can be reversed by taking steps immediately.

How can you tell if your betta fish is recovering from being underweight?

If you are looking after your undernourished betta fish properly, they will recover in no time. You can easily tell by observing them:

  • Betta fish will weigh between 2-4 grams and will look healthy.
  • Bettas’ concave bodies will regain their normal shape like before and make them look healthy and beautiful again.
  • Bettas’ tail, which became thin, will also look in proper shape.
  • Betta fish will become energetic again and will swim effortlessly with those massive fins, which need enormous energy to drag them.
  • They will regain their colors and will look colorful again.

It is not at all difficult to care for an undernourished or underweight betta fish. All you want to do is to monitor them daily, if they look feeble take necessary actions asap.

Consult your vet on what could be the exact reason behind this weight loss and how to recover it from a malnourished condition to a healthy betta fish again.

Feed them high-quality pellets and live food in proper amounts by checking the labels. Make sure you are feeding them on time without skipping their meals. Skipping their meals due to busy lifestyles is a common problem behind an underweight fish.

You have to take out time to feed your fish on time and if you can’t then purchase an automatic fish feeder and adjust it according to fish requirements. By installing a fish feeder you will not have to worry about feeding a fish or skipping its meals due to busy life or if you are vacationing.


  • Overfeeding leads to various health concerns in bettas fish but underfeeding is also dangerous to bettas health. 
  • You should feed your betta fish high-quality pellets and include more proteins in their diet.
  • Quarantine live food before feeding but if you don’t want to quarantine, you can feed frozen or freeze-dried food to your fish.
  • Make sure to defrost or thaw frozen food before feeding your betta fish.
  • Feed only what is digestible and give them ample time to finish their food.
  • Always check food labels for expiry dates and the amount you can feed them.

Frequently asked questions

What is the weight of a healthy betta fish?

The weight of a healthy betta fish is between 2-4 grams.

How many times can you feed live food to underweight betta fish?

You can feed live food to your betta fish once or twice a week.

Do underweight betta fish swim effortlessly?

No, underweight betta fish cannot swim effortlessly, as their huge pectoral fins require enormous energy to drag those fins.

What is the best live food protein source for a betta fish?

A mosquito that has fallen accidentally into a betta tank is the best live protein source for a betta fish.