The short answer
A betta can have tankmates, but only in a tank of 40 litres (10 gallons) or more, well planted and gently filtered. In a smaller tank a betta is best kept alone. When there is room, the calmest, most reliable companions are:
- Otocinclus or corydoras (peaceful bottom feeders)
- Kuhli loaches (shy, snake-like, harmless)
- Small, non-flashy rasboras like harlequin or chili rasboras
- Nerite snails or amano shrimp as cleanup crew
Match the temperament, not just the size
Bettas are territorial and have poor eyesight for detail, so they react to movement and bright, trailing fins. Avoid anything that looks like a rival or a snack. That rules out other bettas, male guppies and endlers, fin-nipping barbs (tiger barbs especially), and fast, boisterous danios that stress a slow-swimming betta. Every betta is an individual — some tolerate tankmates, some never will — so always have a backup plan (a spare tank or divider) in case yours turns aggressive.
Setting it up for success
Give the tank plenty of plants, caves and sightline breaks so fish can stay out of each other’s way, and keep the flow gentle — bettas are weak swimmers with heavy fins. Add the tankmates first and the betta last where possible, so it doesn’t treat newcomers as intruders in its territory. Feed a varied diet so no one goes hungry and turns to fin-nipping; see our fish food hub.
Stock lightly and don’t overcrowd — read how many fish you can keep before adding a group. For more on the fish itself, see our betta care guide, and for a related question, can a betta live with other fish?