Aquariumanabantoid · freshwater
Betta: adult size, tank size & tankmates
The Betta (Betta splendens) grows to about 3.3 in (7 cm SL). It needs a tank at least 18 inches long and about 11 gallons. It doesn't need a group of its own kind, at 72–86°F.
How big it really gets
Drawn to scale against common tank lengths. Green bars meet the minimum tank length from our sources.
Needs special care. Routinely sold for tiny bowls, cups and jars; SF minimum is a 45x30 cm tank and SF says it is not a standard community fish.
Will it fit your tank?
Quick facts
- Adult size
- 3.3 in (7 cm SL)
- Minimum tank
- 18 inches long and about 11 gallons
- Temperature
- 72–86°F
- pH
- 6–8
- Hardness
- 1–15 dGH
- Group size
- 1 (solitary or pair)
- With other fish
- semi-aggressive
- With its own kind
- aggressive
- Swims
- top of the tank
- Diet
- carnivore
- Care level
- intermediate
- Lifespan
- 2 years
Watch for: long fins that nippers target · eats shrimp · jumps, so keep a lid
Betta tankmates
Checked with the same rules as our tank builder: temperature overlap, pH and hardness, predation and mouth size, fin-nipping and temperament. Tank size is left out here; check it in the builder.
Good tankmates
- Cherry BarbAdult ~2.4 in · 68–81°F
- Rummy-nose TetraAdult ~2.4 in · 73–79°F
- GuppyAdult ~2.8 in · 63–82°F
- PlatyAdult ~2.4 in · 68–79°F
- Honey GouramiAdult ~2.6 in · 72–81°F
- Dwarf GouramiNeeds careAdult ~4.2 in · 72–81°F
- Pearl GouramiAdult ~5.7 in · 75–86°F
- Bolivian RamAdult ~3.8 in · 75–82°F
- KribensisAdult ~4.7 in · 75–81°F
- AngelfishNeeds careAdult ~7.1 in · 75–86°F
Use caution
- Neon TetraBetta can bully smaller, peaceful Neon Tetra.
- Cardinal TetraBetta can bully smaller, peaceful Cardinal Tetra.
- Harlequin RasboraBetta can bully smaller, peaceful Harlequin Rasbora.
- Ember TetraBetta can bully smaller, peaceful Ember Tetra.
- Chili RasboraBetta can bully smaller, peaceful Chili Rasbora.
- Celestial Pearl DanioBetta can bully smaller, peaceful Celestial Pearl Danio.
- Black Neon TetraBetta can bully smaller, peaceful Black Neon Tetra.
- Glowlight TetraBetta can bully smaller, peaceful Glowlight Tetra.
Avoid
- Cherry ShrimpBetta will eat Cherry Shrimp.
- Amano ShrimpBetta will eat Amano Shrimp.
- Zebra DanioNeeds careZebra Danio nips fins, and Betta has long fins.
- Tiger BarbNeeds careTiger Barb nips fins, and Betta has long fins.
- Bamboo ShrimpBetta will eat Bamboo Shrimp.
- Black Skirt TetraBlack Skirt Tetra nips fins, and Betta has long fins.
- Buenos Aires TetraNeeds careBuenos Aires Tetra nips fins, and Betta has long fins.
- Convict CichlidNeeds careConvict Cichlid nips fins, and Betta has long fins.
All 105 species we checked against the Betta
| Species | Verdict | Why |
|---|---|---|
| Angelfish | Compatible | No conflicts found |
| Assassin Snail | Compatible | No conflicts found |
| Bala Shark | Compatible | No conflicts found |
| Bleeding Heart Tetra | Compatible | No conflicts found |
| Blood Parrot Cichlid | Compatible | No conflicts found |
| Boesemani Rainbowfish | Compatible | No conflicts found |
| Bolivian Ram | Compatible | No conflicts found |
| Bristlenose Pleco | Compatible | No conflicts found |
| Bronze Cory | Compatible | No conflicts found |
| Cherry Barb | Compatible | No conflicts found |
| Clown Loach | Compatible | No conflicts found |
| Clown Pleco | Compatible | No conflicts found |
| Cockatoo Dwarf Cichlid | Compatible | No conflicts found |
| Common / Comet Goldfish | Compatible | No conflicts found |
| Common Pleco | Compatible | No conflicts found |
| Congo Tetra | Compatible | No conflicts found |
| Denison Barb | Compatible | No conflicts found |
| Discus | Compatible | No conflicts found |
| Dwarf Gourami | Compatible | No conflicts found |
| Dwarf Neon Rainbowfish | Compatible | No conflicts found |
| Electric Blue Acara | Compatible | No conflicts found |
| Firemouth Cichlid | Compatible | No conflicts found |
| Forktail Blue-eye | Compatible | No conflicts found |
| Giant Danio | Compatible | No conflicts found |
| Glass Catfish | Compatible | No conflicts found |
| Gold Barb | Compatible | No conflicts found |
| Guppy | Compatible | No conflicts found |
| Hillstream Loach | Compatible | No conflicts found |
| Honey Gourami | Compatible | No conflicts found |
| Japanese Trapdoor Snail | Compatible | No conflicts found |
| Julii Cory | Compatible | No conflicts found |
| Kissing Gourami | Compatible | No conflicts found |
| Kribensis | Compatible | No conflicts found |
| Kuhli Loach | Compatible | No conflicts found |
| Malaysian Trumpet Snail | Compatible | No conflicts found |
| Molly | Compatible | No conflicts found |
| Moonlight Gourami | Compatible | No conflicts found |
| Nerite Snail | Compatible | No conflicts found |
| Panda Cory | Compatible | No conflicts found |
| Pearl Danio | Compatible | No conflicts found |
| Pearl Gourami | Compatible | No conflicts found |
| Peppered Cory | Compatible | No conflicts found |
| Pictus Catfish | Compatible | No conflicts found |
| Platy | Compatible | No conflicts found |
| Rainbow Shark | Compatible | No conflicts found |
| Ramshorn Snail | Compatible | No conflicts found |
| Red-Tail Shark | Compatible | No conflicts found |
| Rosy Barb | Compatible | No conflicts found |
| Rummy-nose Tetra | Compatible | No conflicts found |
| Scissortail Rasbora | Compatible | No conflicts found |
| Siamese Algae Eater | Compatible | No conflicts found |
| Sterbai Cory | Compatible | No conflicts found |
| Swordtail | Compatible | No conflicts found |
| Three-spot Gourami | Compatible | No conflicts found |
| Tinfoil Barb | Compatible | No conflicts found |
| Upside-down Catfish | Compatible | No conflicts found |
| Variatus Platy | Compatible | No conflicts found |
| Weather Loach | Compatible | No conflicts found |
| African Dwarf Frog | Caution | Betta can bully smaller, peaceful African Dwarf Frog. |
| Black Neon Tetra | Caution | Betta can bully smaller, peaceful Black Neon Tetra. |
| Bumblebee Goby | Caution | Betta can bully smaller, peaceful Bumblebee Goby. |
| Cardinal Tetra | Caution | Betta can bully smaller, peaceful Cardinal Tetra. |
| Celestial Pearl Danio | Caution | Betta can bully smaller, peaceful Celestial Pearl Danio. |
| Chili Rasbora | Caution | Betta can bully smaller, peaceful Chili Rasbora. |
| Chinese Algae Eater | Caution | Chinese Algae Eater grows 4× longer than Betta and may treat it as food. |
| Clown Killifish | Caution | Betta can bully smaller, peaceful Clown Killifish. |
| Ember Tetra | Caution | Betta can bully smaller, peaceful Ember Tetra. |
| Endler's Livebearer | Caution | Betta can bully smaller, peaceful Endler's Livebearer. |
| German Blue Ram | Caution | Betta can bully smaller, peaceful German Blue Ram. |
| Glowlight Tetra | Caution | Betta can bully smaller, peaceful Glowlight Tetra. |
| Harlequin Rasbora | Caution | Betta can bully smaller, peaceful Harlequin Rasbora. |
| Head-and-tail-light Tetra | Caution | Betta can bully smaller, peaceful Head-and-tail-light Tetra. |
| Lambchop Rasbora | Caution | Betta can bully smaller, peaceful Lambchop Rasbora. |
| Lemon Tetra | Caution | Betta can bully smaller, peaceful Lemon Tetra. |
| Marbled Hatchetfish | Caution | Betta can bully smaller, peaceful Marbled Hatchetfish. |
| Mystery Snail | Caution | Betta (pH 6–8) and Mystery Snail (pH unknown) prefer different pH.; Betta (1–15 dGH) and Mystery Snail (unknown dGH) prefer different water hardness. |
| Neon Tetra | Caution | Betta can bully smaller, peaceful Neon Tetra. |
| Odessa Barb | Caution | Betta can bully smaller, peaceful Odessa Barb. |
| Otocinclus | Caution | Betta can bully smaller, peaceful Otocinclus. |
| Paradise Fish | Caution | Betta and Paradise Fish only share 72–72°F. That's a tight window. |
| Pristella Tetra | Caution | Betta can bully smaller, peaceful Pristella Tetra. |
| Pygmy Cory | Caution | Betta can bully smaller, peaceful Pygmy Cory. |
| Silver Hatchetfish | Caution | Betta can bully smaller, peaceful Silver Hatchetfish. |
| Sparkling Gourami | Caution | Betta can bully smaller, peaceful Sparkling Gourami. |
| White Cloud Mountain Minnow | Caution | Betta and White Cloud Mountain Minnow only share 72–72°F. That's a tight window.; Betta can bully smaller, peaceful White Cloud Mountain Minnow. |
| Amano Shrimp | Avoid | Betta will eat Amano Shrimp. |
| Bamboo Shrimp | Avoid | Betta will eat Bamboo Shrimp. |
| Black Skirt Tetra | Avoid | Black Skirt Tetra nips fins, and Betta has long fins. |
| Buenos Aires Tetra | Avoid | Buenos Aires Tetra nips fins, and Betta has long fins. |
| Cherry Shrimp | Avoid | Betta will eat Cherry Shrimp. |
| Convict Cichlid | Avoid | Convict Cichlid nips fins, and Betta has long fins. |
| Crystal Red Shrimp | Avoid | Betta will eat Crystal Red Shrimp. |
| Diamond Tetra | Avoid | Diamond Tetra nips fins, and Betta has long fins. |
| Electric Yellow Lab | Avoid | Electric Yellow Lab nips fins, and Betta has long fins. |
| Fancy Goldfish | Avoid | Betta (72–86°F) and Fancy Goldfish (50–70°F) need different temperatures. |
| Ghost Shrimp | Avoid | Betta will eat Ghost Shrimp.; Ghost Shrimp nips fins, and Betta has long fins. |
| Iridescent Shark | Avoid | Iridescent Shark eats small fish, and Betta only grows to about 3.3 in. |
| Oscar | Avoid | Oscar eats small fish, and Betta only grows to about 3.3 in. |
| Pea Puffer | Avoid | Pea Puffer nips fins, and Betta has long fins. |
| Penguin Tetra | Avoid | Betta can bully smaller, peaceful Penguin Tetra.; Penguin Tetra nips fins, and Betta has long fins. |
| Serpae Tetra | Avoid | Serpae Tetra nips fins, and Betta has long fins. |
| Silver Tip Tetra | Avoid | Silver Tip Tetra nips fins, and Betta has long fins. |
| Tiger Barb | Avoid | Tiger Barb nips fins, and Betta has long fins. |
| Yoyo Loach | Avoid | Yoyo Loach nips fins, and Betta has long fins. |
| Zebra Danio | Avoid | Zebra Danio nips fins, and Betta has long fins. |
Care notes
Needs: Best in its own tank; keep well covered with an air gap above the water (needs humid air; excellent jumper). Gentle flow (air-driven sponge filter). Avoid long-finned or colourful tankmates a male may see as rivals. Do not overfeed (prone to obesity).
Group: Males: SF says only a single individual can be kept per tank in most cases, and sexes are kept apart except for breeding; FishBase: males fight. group_min 1 applies to males. SF does not address keeping females together (Fishkeeping World says sororities of 5+, needs space).
Temperament: semi-aggressive toward other fish, aggressive toward its own kind. Lives in the top of the tank.
Common questions
How big does a Betta get?
About 3.3 inches (7 cm SL) as an adult, according to seriouslyfish.com.
What size tank does a Betta need?
At least 18 inches long and about 11 gallons. The smallest standard tank that meets that is a 20 gallon long.
How many Bettas should be kept together?
It can be kept on its own. Males: SF says only a single individual can be kept per tank in most cases, and sexes are kept apart except for breeding; FishBase: males fight. group_min 1 applies to males. SF does not address keeping females together (Fishkeeping World says sororities of 5+, needs space).
What fish can live with a Betta?
Species that passed every check include Cherry Barb, Rummy-nose Tetra, Guppy, Platy, Honey Gourami, Dwarf Gourami.
Gear for a Betta setup
TankSmallest standard tank that meets its minimum: 20 gallon long (30 in long).Find on Amazon →HeaterAbout 100 W for 20 gallons, holding 72–86°F.Find on Amazon →LidIt jumps. A full lid keeps it in the tank.Find on Amazon →FoodMeaty frozen foods suit its diet.Find on Amazon →Test kitCheck ammonia, nitrite and pH. Cycle the tank before adding fish.Find on Amazon →
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Related guides
Sources
Values come from these pages, in our own words. Status: verified (independent spot-check). Last reviewed 2026-10-12.
- seriouslyfish.com /species/betta-splendens/
- fishbase.se /summary/Betta-splendens.html
- fishkeepingworld.com /betta-fish/