5 Tips for Betta Fish Tank Size

With this article we hope to help buyers understand the betta fish tank size requirements. Please do not try raising betta fish in a small tank of only a few gallons (or even less). Pet shops and other retailers sell betta fish in small containers, but – What works on a temporary basis, will not always work long-term.

How big should a betta fish tank be?

We recommend betta fish tank size of 20 – 25 gallons of water at a minimum depending on the size and number of your betta fish. Select a tank that is longer than it is tall. This will allow the fish adequate room for swimming and ensure that their fins do not touch the sides when swimming.

A small home aquarium will accommodate a betta fish.

Your betta will need enough room to easily swim around. Some good fish tank options start at around $40 – $50 suitable for a single betta. The best tank size for betta fish depends on the number of fish. Increase the number of gallons as you add more fish (Ex. 2 fish 30 – 35 gallons, 3 fish 40 – 45 gallons, and on).

Do not try to keep bettas in an undersized tank.

Pet stores sell betta tanks but stick to traditional fish aquariums. Your fish will appreciate you for it and reward you with brighter coloration, higher activity levels, and longer lives. We recommend a 10-gallon fish tank as the bare minimum size a betta fish needs. A 5-gallon betta fish tank is not ideal for long-term fish keeping.

Wondering about Giant betta fish tank size? The same guidelines hold true, but since Giant bettas grow to 3.5 – 4 inches, lean toward the larger sized tanks recommended above with the minimum we recommend being 20 gallons.

Image by endri yana yana from Pixabay

Considerations for betta fish tank size

Unclean conditions or unhealthy water parameters cause stress for your fish. Bad water also contributes to conditions for other common fish illnesses that cause ich and fin rot.

You do not need a 100-gallon tank for a single betta fish, but the tank needs to hold appropriate water volume in accordance with the number of fish you keep. And water parameters need maintenance at optimal levels for optimal fish health.

  • Nitrite near 0 ppm
  • Nitrate near 0 ppm
  • Phosphate < 1 ppm
  • Ammonia near 0 ppm
  • PH near 7.0

While the betta fish tank size varies according to available space, budget, and personal preferences, clearly the more water volume in the betta tank, the easier it will be to maintain correct water parameters.

If you use well water at your residence, test it using aquarium water quality kit before using it in your betta fish tank. Betta fish tank size is secondary to having a good, high-quality water to put in it.

The same goes for your municipal water supply. Test the water coming out of the faucet you will use to fill your fish tank. Surprisingly, some water supplies make fish rearing more difficult.

For example, if your tap water has a high phosphate content, research what actions you should take to offset that to improve the water quality for your betta fish.

As an example:

  • Removing 5 gallons of water from a 50-gallon tank represents 10% of the volume.
  • Removing 5 gallons of water from a 10-gallon tank represents 50% of the volume.

Note: Removing more than 50% of water volume in your fish tank at one time leaves little room for error. Beginners to fishkeeping should aim for 10 – 25% water changes. Changing a couple times during the week, if needed, is better than waiting three weeks and doing an 80 – 100% water change.

Using the correct water treatment product for your aquarium will ensure the water you are adding is acceptable for your fish. Before purchasing your new bettas, set-up the aquarium in advance and learn to “cycle” it to promote growth of beneficial bacteria and create optimal conditions prior to adding new fish.

Research “new tank syndrome” and learn how to minimize it.

Please leave the big volume water changes to the experts that have years of experience.

Fishkeeping tip: Beginners often struggle to maintain good water quality. Betta fish tank size is important, but many other factors contribute to success in fishkeeping.

  • Don’t be too hard on yourself, especially if you are new to aquarium keeping.
  • Learn everything you can about fish keeping before purchasing your new betta fish.
  • If you experience difficulty, re-group and don’t repeat the same mistakes.
  • Join a betta fishkeeping forum, discussion board, or social media group as a learning tool.
  • Don’t stop learning about your betta fish and how to keep it healthy and happy.
Image by Seno Aji from Pixabay

Select a fish tank with an adequate lid. It keeps the fish inside the tank (they can jump) and it keeps predators and pests out (i.e., house cats being a likely threat to your fish). It also helps keep unwanted items from accidentally falling into the fish tank.

Gravel looks nice in aquariums, but we recommend against using it. Gravel traps debris and makes cleaning the water much more difficult. Some fish have swallowed gravel resulting in death. Many fish keepers are choosing bare bottomed tanks without any gravel or sand at all.

Choose a sturdy tank stand. A tank full of water weighs a lot more than you may think. If a gallon of water weighs just under 7 pounds, a 20-gallon tank weighs almost 140 pounds before adding a filter, air stones, sponge filter, or the tank’s lid!

Do betta fish grow to the size of their tank?

Healthy betta fish grow bigger than unhealthy ones. Most bettas are similar in size, but unhealthy fish will often have tattered and shortened fins that definitely make the fish look smaller.

If you want your fish to look their best, no matter their size, take special care to provide clean tank conditions.

If the fish tank is too small, the fish will not grow to their maximum size.

Best water temperature in betta fish tank

In the wild, water temperatures vary more than in a home aquarium environment, but the changes are usually very subtle and take place over hours, days, or even weeks.

Sudden temperature changes in a betta tank (or any fish tank really) can cause harm to your fish. Sometimes the result is immediate and sometimes it takes places over days or weeks in the case of repeated temperature variation when performing water changes. The betta fish tank size directly affects water temperature.

  • Water temperatures in your betta tank should range between 75 – 80F
  • Always check the water temperature of any water added to the tank
  • Water temperature is difficult to gauge accurately without a thermometer
  • Make sure your thermometer is accurate (test in boiling water, at time of boil water is 212F

A 100-watt heater will work fine in a small tank. If you keep bettas in a 50-gallon or larger tank, you may need a 150 watt or larger tank heater. A large 100-gallon betta fish tank size may even require multiple heaters to maintain an even temperature throughout the tank.

Image by JOMAS from Pixabay

How often should you clean a betta fish tank?

  • The best answer is: Whenever the water needs it.
  • The practical answer: When water parameters indicate the water needs it.

The subtle difference between the two relies on fish keepers monitoring the water conditions daily with new fish, or every two or three days at a minimum with fish that have adjusted to their new living conditions.

Keeping a journal of the nitrates, nitrates, phosphates, ammonia, and PH will help with monitoring over time and provide a reference point to fall back on if you notice changes in your fish.

If you fish change behavior, check the water parameters. Unhealthy water conditions will result in unhealthy fish. Fish health reveals itself primarily by the activity level (swimming vs. floating), their position within the aquarium (sitting at the bottom or at the top of the tank), how their fins look (tattered and split fins vs smooth flowing), or when other skin conditions become evident (white spots, cloudy substances, discoloring, and other indicators).

If your fish do not look right, they probably aren’t.

Do you need bubbles in a betta fish tank?

Bubbles in a fish tank help with water circulation, degassing, and oxygenation. Adding a water stone or bubbler to a betta tank that already has a mechanical filtration is not necessary, although it should not hurt.

Betta fish breath via gills like most aquarium fish and being labyrinth breathers, meaning they intake oxygen from the water surface by taking big gulps, they also breath through their mouths. For most fish, seeing them gulping at the surface is cause for alarm, but for bettas it is normal and not cause for alarm.

Your choice of betta fish tank size dictates the level of oxygen available for fish living in it. You’re unlikely to have too much oxygen but having too little is a possibility.

Image by Seno Aji from Pixabay

Do betta fish tanks need a filter?

Yes. A properly sized mechanical filter coinciding with the betta fish tank size will provide the necessary circulation and promote good bacteria growth to maintain good water parameters.

Mechanical filters should circulate at least 125% of the water volume per minute of activation. For example, a 20-gallon tank should have a filter capable of circulating at least 25-gallons per minute.

For long term betta keeping, best practice recommends filtration. Flow-thru filtering systems are affordable and easy to install.

Forcing betta fish to rely on gulping air to breath is only a temporary solution. It works in their natural topical habitat only because nature provides adequate filtration from plants and other healthy bacteria. Jumping from water puddle to water puddle works in nature but forcing your betta to struggle for air is not necessary in a home aquarium. Most experienced fish keepers would also call it inconsiderate and even inhumane.

Wrapping Up

Bettas are unique fish in the home aquarium hobby. Their beautiful colors add wonderfully to any aquascape.

Please do not keep fish in a 3-gallon betta tank. A 5-gallon betta fish tank size is better, but still not recommended for longer periods. And for reference, there aren’t many fish that can live long-term in a 5-gallon fish tank. It is stressful for even small fish because smaller tanks require diligent water maintenance practices and adherence to strict water change schedules.

Simple guidelines for each betta care

  • Adequate betta fish tank size
  • Clean water
  • Good temperature
  • Filtration
  • Constant monitoring
  • Taking appropriate action at the appropriate time
  • Do not let your fish suffer from your lack of awareness

What not to do with your bettas

  • Don’t ignore water quality
  • Don’t keep your fish tank in direct sunlight
  • Think twice about using a gravel bottom (difficult to keep clean)
  • Establish a schedule for regular water changes

Hopefully, this article answers questions you have about keeping bettas as pets, the best betta fish tank size, and provides the confidence to help you do it more successfully.

If betta fish aren’t your ideal pet, this review of apartment pets might help.