How Many Gallons Do a Betta Fish Need?

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A single betta needs at least 5 gallons. A betta that shares its tank with other fish needs at least 45 litres, which is about 12 US gallons. The 5 gallon floor is this site’s welfare rule and matches the University of Illinois veterinary teaching hospital article, which gives a 5 gallon minimum and says bowls are not suitable. The 45 litre figure comes from the Wikipedia species overview. We do not recommend any tank under 5 gallons, so this guide lists only 5 to 10 gallon tanks, starting with the Marineland Portrait 5 gallon kit. None of the tanks here reaches the tank-mate size.

At a glance

Minimum tank sizes and water settings stated in this guide.

Setup	Minimum or range	Note from the post
One betta alone	5 gallons	Site minimum; more water is easier to keep stable
Betta with other fish	45 litres (about 12 US gallons)	Species overview figure; no tank in this guide is that large
Bowl or vase	Not suitable	Per the Illinois article cited
Water temperature	76 to 81 F	Illinois article; a heater is needed
New biofilter	6 to 8 weeks to build	University of Florida IFAS publication

Listed gallons are the maker’s capacity figure, and substrate and decor reduce the water you actually have.

How many gallons: the decision in four lines

One betta, nothing else in the tank: 5 gallons is the minimum. More water is fine and easier to keep stable.
One betta plus other fish: at least 45 litres, about 12 US gallons, per the species overview. No tank in this guide is that large, and the two 10 gallon tanks hold about 38 litres, so do not use them for tank mates. See tank mates for a male betta.
Two or more bettas: separate tanks. The overview says males frequently fight when kept together and females can be territorial in confined spaces.
Less than 5 gallons, a bowl or a vase: not recommended here, whatever the box says. The Illinois article says bowls are not suitable.

Listed gallons are a capacity figure from the maker. Once substrate, rocks and decor are in, you have less water than the label says, which is one more reason to treat 5 gallons as the bottom of the range rather than the target.

Gallons are not the whole setup

The Illinois article also gives a water temperature of 76 to 81 F for a betta and says a heater is needed. A tank can meet the volume rule and still fail if it has no heater, so plan the heater with the tank. Our betta heater guide lists heaters, and none of the tanks below states one in its listing.

Water quality is the second part. The University of Florida IFAS ammonia publication says ammonia is colorless and odorless even at levels that are toxic to fish, so the only way to know is to test. It also says a new biofilter needs six to eight weeks to build enough bacteria to reduce ammonia and nitrite effectively, and that nitrite is toxic to fish at levels as low as 0.10 mg/L. A bigger volume gives you more room for error, but it does not remove the need to test during the first weeks.

Step by step: setting up the right-size tank

1. Decide how many fish. One betta alone: 5 gallons or more. A betta with others: 12 US gallons (45 litres) or more.
2. Measure the space. Use the outside dimensions in the listing, not the gallons. A tank that is tall and narrow and a tank that is long and low can have similar gallons and need very different shelves.
3. Check what is included. A kit’s listing says whether a filter, light and lid come in the box. Buy any missing item before the fish arrives.
4. Add a heater and a thermometer. The Illinois article gives 76 to 81 F.
5. Run the tank before adding the fish. The IFAS publication’s six to eight weeks for a new biofilter is the reason not to rush, and testing is the only way to see ammonia.

Five tanks that meet the gallon rule

1. Marineland Portrait 5 gallon fish tank kit

5 gallons, glass, black. Size: 9.99 x 9.67 x 17.2 inches. Weight: 16 pounds.
Includes LED light, filtration and a filter cartridge; fits Marineland Rite-Size Z cartridges.

The listing describes daylight and moonlight LED modes, hidden three-stage filtration, a hinged light and a sliding glass canopy. It has the smallest footprint of the glass tanks here, which suits a desk or a narrow shelf.

Limitation: it is tall for its base, and the listing does not mention a heater. Reaching the bottom of a tank this tall is harder than with a long, low tank.

View the Marineland Portrait kit on Amazon (affiliate link)

2. FS&AQ 5 gallon betta fish tank with filter, light and lid

5 gallons, glass. Size: 15.15 x 7.48 x 10.23 inches.
Includes filter, light, lid and an aquarium mat; the listing calls the filter a waterfall-style system with adjustable flow.

The listing says the back panel is black glass to hide the filter and cord, and the other three sides are clear. The adjustable flow is the most relevant feature for a betta keeper, because the listing offers a way to turn the water movement down. The mat is included to cushion the base.

Limitation: the listing gives no flow rate and no heater, so the adjustable flow is a feature name rather than a number you can compare. The listing says the lid is custom-fit to stop jumping and reduce evaporation, but it does not give the lid’s opening size.

View the FS&AQ 5 gallon tank on Amazon (affiliate link)

3. YHDSYN 6 gallon starter kit

6 gallons, plastic (AS, PET and polypropylene). Size: 19.5 x 8.4 x 8.4 inches. Weight: 5.7 pounds.
Includes air pump, filter and light; four-layer hanging filter; 3-color LED with 9 dimming steps.

The extra gallon over a 5 gallon tank and the 19.5 inch length give a betta the most horizontal room of the three tanks under 10 gallons. The listing names an adjustable pump and extra filter media for beneficial bacteria.

Limitation: the listing also markets the tank for tetras, danios and shrimp, which is general copy. The listing does not mention a lid or a heater.

View the YHDSYN 6 gallon kit on Amazon (affiliate link)

4. Vimvins 10 gallon glass tank with filter, light and lid

10 gallons (about 38 litres), glass. Size: 19.68 x 10.23 x 11.81 inches. Weight: 18 pounds.
Includes filter, light and lid; two-stage filtration; 15W LED with 3 color modes.

This is a single-betta tank with more room. It is not a tank-mate tank: 10 US gallons is about 38 litres, below the 45 litres the species overview gives for a betta kept with other fish. The listing describes quiet two-stage filtration and a one-touch light.

Limitation: no heater is listed, and 10 gallons of water plus glass is much heavier than any of the smaller tanks here. Make sure the surface can take it.

View the Vimvins 10 gallon tank on Amazon (affiliate link)

5. LAQUAL 10 gallon ultra clear glass tank set

10 gallons, low-iron glass, 5 mm thick, rimless. Size: 20 x 10.4 x 12 inches.
Includes 3 adjustable covers, 4 cover clips, a floating feeding ring (3 inch diameter), 2 sponges, a scraper, tweezers and a siphon.

This is a tank-and-tools set. The listing names bettas among the animals it suits and says the covers help stop fish jumping. Of the five tanks, it comes with the most cleaning tools. Like the Vimvins 10, it holds about 38 litres, so it is below the tank-mate figure.

Limitation: the listing does not state a filter, light or heater, so you would need to buy all three. Choose it if you already own equipment or want to match it to a specific filter, not as a ready-to-run kit. Filters are not covered by this listing.

View the LAQUAL 10 gallon set on Amazon (affiliate link)

Which to pick

Desk or narrow shelf, one betta: the Marineland 5 gallon, for its 9.99 inch width.
Ready to run, long and low: the FS&AQ 5 gallon, which includes filter, light, lid and mat.
Most horizontal room under 10 gallons: the YHDSYN 6 gallon.
Largest tank here, one betta: the Vimvins 10 gallon if you want a kit, the LAQUAL 10 gallon if you want to choose your own equipment.
Betta plus tank mates: none of the tanks here reaches 12 US gallons. Find a larger tank before you choose the other fish.

FAQ

Is 5 gallons enough for one betta?

It meets this site’s minimum and the minimum in the Illinois article. More water is easier to keep stable. See how much space a betta needs for more.

Can a betta live in a bowl?

The Illinois article says bowls are not suitable, and this site does not recommend them.

What temperature should the water be?

The Illinois article gives 76 to 81 F and says a betta needs a heater. None of the five tanks above lists one.

How long before a new tank is ready for fish?

The IFAS publication says a new biofilter takes six to eight weeks to build enough bacteria to reduce ammonia and nitrite effectively. It also says testing is the only way to detect ammonia.

Does a bigger tank mean fewer tests?

No. For the production systems it covers, the IFAS publication says to test weekly and immediately whenever fish appearance or behavior changes, including reduced feeding.

Bottom line

Start with 5 gallons for one betta. Other fish need at least 45 litres (about 12 US gallons), and none of the tanks here reaches that size, so plan a larger tank before adding tank mates. Choose by footprint and what is included, add a heater, and test the water. Do not buy anything under 5 gallons, and do not treat a bowl as a home.

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