Tank Mates

Betta Gillfriend care rules: one betta per tank. Mirror or flare practice: one 2-minute session a day, with at least 2 rest days a week. Train: up to 10 minutes a week.

The honest answer to "what can live with my betta?" is: often nothing, and that's fine. Bettas don't get lonely. A male betta is happiest with his own well-planted tank. If you'd like tank mates, it can work, but it depends on your individual betta's temperament, the tank size, and choosing species carefully.

Warning: Never keep two male bettas together. Males fight until one is badly injured or killed (OATA), and research found that even very large aquariums didn't let two males live together peacefully. Divided tanks need a solid, gap-free divider. A see-through divider means non-stop flaring.

The golden rules

Start with enough space. RSPCA Australia recommends at least 40 L (about 10 US gallons) for a betta in a community, and more is better. Many keepers prefer 20 gallons or more for a comfortable community.
Choose peaceful, slow, non-nippy species. Bettas' long fins are a target. OATA notes male bettas are usually not aggressive to other species but are often the victim of fin nipping, which causes stress, disease and death.
Avoid anything colourful, long-finned, or betta-like. Your betta may see it as a rival.
Match the water. Tank mates must suit the same temperature (76–81°F / 24–27°C) and water chemistry.
Quarantine every new animal (at least 4 weeks) before adding it. Tank mates are a common way diseases like gill flukes, ich and velvet arrive. See Quarantine.
Have a backup plan. RSPCA Australia advises having a spare tank ready in case it doesn't work out. Some bettas simply won't accept company.
Plant heavily to break up lines of sight and give everyone hiding places.

Compatibility guide

This is a general guide. Individual bettas vary hugely: some ignore everything, others attack anything that moves.

Tank mate	Compatibility	Notes
Nerite snails, mystery snails, ramshorn snails	✅ Usually good	Suggested by the Illinois vet hospital. Some bettas nip at snail antennae. Snails add waste, so don't overstock. Snails are killed by copper medications.
Ghost shrimp	⚠️ Often OK	Suggested by the Illinois vet hospital. Some bettas will hunt and eat them.
Cherry and other Neocaridina shrimp	⚠️ Risky	Often eaten, especially babies. Best in a heavily planted, larger tank.
Corydoras catfish	✅ Often good	Suggested by RSPCA Australia. Peaceful bottom dwellers; keep in a group, on smooth sand or gravel, in a bigger tank.
Otocinclus	✅ Often good	Suggested by RSPCA Australia. Small, peaceful algae grazers; need a mature tank with algae and a group.
Neon tetras	⚠️ Sometimes	RSPCA Australia lists them in groups of 5 or more. They're small and fast, and some bettas chase them.
Small peaceful rasboras (e.g. harlequins)	⚠️ Sometimes	Common community choice; keep in a group; watch for chasing.
African dwarf frogs	⚠️ Sometimes	Suggested by the Illinois vet hospital, but they need a bigger tank, are slow eaters, and must not be confused with clawed frogs (which grow large).

Species to avoid

Avoid	Why
Another male betta	Will fight. Never.
Female bettas with a male (permanently)	Males and females fight outside of spawning. We don't recommend it.
Tiger barbs and other barbs	Notorious fin nippers (PetMD).
Serpae, black widow (black skirt) and Buenos Aires tetras	Fin nippers. RSPCA Australia names widow, serpae and cochu blue tetras as unsuitable.
Gouramis	Close relatives with similar behaviour; often fight.
Fancy guppies and other long-finned or brightly coloured fish	May trigger aggression (looks like a rival) or nip fins (PetMD).
Cichlids, large or aggressive fish	Will bully or eat a betta.
Goldfish	Coldwater fish with different needs; very messy.
Fast, boisterous fish (e.g. many danios)	Outcompete bettas for food, stress them, may nip.
Crayfish and crabs	Can catch and injure fins.
Pufferfish	Fin nippers; different needs.

Introducing tank mates

Quarantine the new animal for at least 4 weeks.
Rearrange decor slightly, so territory feels new.
Add the tank mates first if possible, then the betta. Otherwise, add the newcomers with the lights low.
Watch closely for the first hours and days, and then daily: chasing, nipping, fin damage, stress stripes, hiding or missed meals.
Feed carefully, so everyone gets the right food (sinking food for corydoras, etc.) without your betta overeating.
Separate immediately if there is persistent chasing or any fin damage.

Tank mates by tank size

A quick guide to what might work at each size. Always start with a calm betta, quarantine newcomers, and keep a backup tank ready.

Tank size	Realistic options	Notes
Under 19 L (5 US gal)	None	Too small for a betta alone to be ideal; no room for company.
19–29 L (5–7.5 gal)	One nerite snail or a few ramshorn snails	Snails add waste; keep numbers low. Shrimp may be eaten.
38 L (10 gal)	Snails; ghost shrimp or cherry shrimp in a heavily planted tank (some will be eaten)	RSPCA Australia's minimum for a betta community is about 40 L. Small schooling fish are a squeeze here.
57–75 L (15–20 gal)	Snails, shrimp, a group of pygmy or panda corydoras (6+), otocinclus (6+) in a mature tank, or a small school of harlequin rasboras or ember tetras	Lots of plants to break sight lines. Watch the first weeks closely.
75 L+ (20 gal+)	All of the above, with more space for schools of 8–10	More room = fewer squabbles, but some bettas still won't share.

Evidence note: These sizes are cautious keeper guidelines built on RSPCA Australia's 40 L community minimum and the "Life in a fishbowl" research on space. There's no study that tests each pairing; your betta's personality is the deciding factor.

Sources

Care guide by Betta Gillfriend (Bespok Labs, BC, Canada). It is general information, not vet advice. If your betta is sick, ask an aquatic vet.