By Tom Whitfield
"What can I keep with my betta?" — the honest answer
It's the single most-asked question I get, and it usually arrives the same way: someone has a male betta thriving on his own, the tank looks a bit empty, and they want to know what fish they can add to fill it out. The trouble is that most betta fish tank mates advice online is written with far too much confidence — long lists of "compatible species" presented as guarantees, when the reality is messier and more interesting than that.
I'm Tom, and I keep nano tanks — almost everything I run is under 60 litres — so the betta community tank is squarely my patch. Here's the honest version I'd give a customer in the shop: a single male betta can sometimes share a planted tank with the right calm companions, and sometimes can't, because temperament is an individual thing. Seriously Fish, the independent species reference, puts it bluntly — the betta is "not recommended for the standard community aquarium" and is often best kept alone [2]. This page is the decision: which betta friendly fish actually work, which to avoid, how much tank you need, and what to do if your particular fish turns out to be a loner. For the fish itself — tail types, heater, buying — see our betta fish UK guide; for keeping a group of females, the female betta guide covers a completely different setup.
Panda cory (Corydoras panda), one of the safest betta tank mates we stock. Peaceful bottom-shoalers like this keep to the floor of the tank and ignore the betta entirely — exactly the temperament you want in a companion. Photo: Tropical Fish Co.
Five things most UK betta tank-mate guides never tell you
- A betta's aggression is partly learned, not just inborn. A peer-reviewed 2021 study found that the timing of when a young betta is isolated from a social, enriched environment measurably changes how aggressive it becomes as an adult [3]. That's the science behind why one betta tolerates tank mates and the next won't — it isn't random, but it isn't fully predictable either.
- Bettas are not lonely without company. They're territorial, largely solitary fish — a male alone in a warm, planted tank is a contented animal, not a sad one [2]. Tank mates are for your enjoyment and a fuller-looking aquarium, never for the betta's wellbeing. Drop the guilt; it leads to bad decisions.
- The trigger is fins and colour, not size. A male betta attacks things that look like a rival male — long flowing fins and bright trailing tails. That's why a tiny male guppy is a worse idea than a much larger, plain-finned fish. The classic betta-plus-guppy disaster is the colour-and-finnage trigger, not a size mismatch [2].
- Nerite snails are the one genuinely bulletproof tank mate. Their hard shell and grazing habit keep them out of trouble, and crucially they won't breed in fresh water, so they can't overrun the tank [1]. If you want something alive in there alongside a betta that won't tolerate fish, a nerite is the answer.
- UK tap water already suits both the betta and its tank mates. Bettas tolerate pH 6.0–8.0 and hardness 5–19 dGH [1], which comfortably overlaps the corydoras, tetras and shrimp on this page — and Britain's hard southern supplies [5] sit inside that shared window. You're not juggling two incompatible water chemistries; you're keeping fish that already share one.
Best betta tank mates — the species that actually work
These are the companions I'd actually put with a single male betta, all of which we stock. They share three traits: peaceful temperament, no long flowing fins, and a comfort zone that overlaps the betta's 24–27 °C. "Level" is where they live in the tank — bettas patrol the top and middle, so bottom-dwellers and tight mid-water schools cause the least friction.
| Species | Type | Why it works with a betta | Level |
|---|---|---|---|
| Panda Cory (Corydoras panda) | Catfish | Peaceful bottom-shoaler, no long fins, stays out of the betta's airspace; keep 6+ [1] | Bottom |
| Pygmy Corydoras (Corydoras pygmaeus) | Nano catfish | Tiny (2.5 cm) and busy on the substrate; ideal for smaller betta tanks; keep 8+ | Bottom |
| Ember Tetra (Hyphessobrycon amandae) | Nano tetra | 2 cm, peaceful, warm-water (24–28 °C) — a tight group rarely draws a betta's attention | Middle |
| Neon Tetra (Paracheirodon innesi) | Small tetra | 4 cm, peaceful schooler with no long fins; keep 10+ so they shoal tightly | Middle |
| Black Neon Tetra (Hyphessobrycon herbertaxelrodi) | Small tetra | Hardy 4 cm schooler, calm and plain-finned; happy at the betta's temperature | Middle |
| Nerite Snail (Neritina sp.) | Snail | The safest of all — algae grazer, hard shell, won't breed in fresh water | Bottom |
| Amano Shrimp (Caridina japonica) | Shrimp | Adults (up to 5 cm) are large enough that most bettas ignore them | Bottom |
| Cherry Shrimp (Neocaridina davidi) | Dwarf shrimp | Works with cover and moss — but accept that shrimplets may be eaten | Bottom |
Start with the bottom-dwellers and the snail — corydoras and a nerite are the lowest-risk additions to almost any betta tank. Add a tight mid-water school (ember, neon or black neon) once the betta is settled, and treat dwarf shrimp as a bonus rather than a guaranteed colony.
Fish to AVOID with bettas — the four no-go groups
This list is where betta communities are won or lost. Get the species selection wrong and no amount of planting will save it. Avoid:
- Fin-nippers. Tiger barbs are the classic offender — they nip trailing fins relentlessly, and a male betta's flowing tail is an irresistible target. Serpae tetras and many barbs behave the same way. A nipped betta develops fin rot and chronic stress [2].
- Long-finned or brightly-coloured fish. Male guppies, fancy goldfish, other long-finned ornamentals — the betta reads their trailing fins and bright colour as a rival male and attacks [2]. (Fancy goldfish are also coldwater fish and the wrong temperature anyway.) This is the single most common stocking mistake I'm asked about.
- Aggressive or territorial fish. Anything that will fight back — many cichlids, larger gouramis, aggressive barbs — turns the tank into a war. The betta either loses or spends its life fighting, and both outcomes are welfare failures.
- Another betta with a male. A second male is a death sentence; a female with a male, outside of brief supervised breeding, ends badly too. Two males flare, lock jaws and tear each other apart on sight — it is literally what the Siamese fighting fish was bred to do [4]. One betta per tank.
The two mistakes that cause the most heartbreak: adding male guppies (their colour and long tails trigger the betta into relentless attacks), and the belief that two male bettas can share a tank "if it's big enough." They can't — not in any tank, at any size. Two males will fight until one is dead [4]. If you want more than one betta in the home, you need more than one tank. There is no exception to this.
Tank size and setup for a betta community
A single male betta alone is fine in around 19 litres, heated and filtered [4]. The moment you add tank mates, that floor rises — you need more water for stability and, just as importantly, more floor space and planting to break up sight-lines. My realistic minimum for a genuine betta community is 38 litres, and 40–60 litres is far better. Here's how I set one up:
- Plant it heavily. Dense planting, driftwood and a leaf hammock break the betta's line of sight so he can't patrol the whole tank as one territory. Broken sight-lines are the single biggest factor in whether a community holds together [6].
- Match the temperature to the betta. Hold the tank at 24–27 °C — the betta sets the range, and every species on this page is comfortable in it [1]. Neon tetras tolerate the cooler end; ember tetras and the shrimp prefer the warmer end.
- Keep flow gentle. Bettas come from slow, warm water and tire in a strong current; a sponge filter or a baffled internal suits both the betta and small tetras.
- Give bottom-dwellers their own space. A soft sand or fine-gravel substrate keeps corydoras barbels healthy, and the busy floor activity draws the betta's attention downward and away from the mid-water school.
For the full betta setup — heater wattage, filter choice, cycling — read our betta fish UK buying guide and the betta fish care guide. New to fishkeeping entirely? The first tropical tank guide walks through a planted community from scratch, and the corydoras care guide covers the bottom-dwellers in depth.
Ember tetras (Hyphessobrycon amandae). Kept in a proper group of 8–10 they shoal tightly and stay calm, which is exactly why a school of small, plain-finned tetras rarely draws a betta's aggression. Six lonely tetras behave very differently from a confident group of ten. Photo: Tropical Fish Co.
Adding tank mates to a betta tank — the protocol
How you introduce companions matters as much as which species you choose. The goal is to stop the betta treating the whole tank as an established territory he must defend. Here's the routine I use:
- Rearrange the décor first. Move the plants, wood and hardscape around so the betta loses his mental map of the tank. A reorienting betta is far less territorial than a settled one [6].
- Add companions as a group, not one at a time. A single new fish gets singled out; a group of ten tetras dilutes any one fish's attention. Add the whole school at once.
- Add tank mates early. Ideally introduce companions before or at the same time as the betta, rather than dropping them into his established tank weeks later. If the betta's already in residence, the décor rearrange in step 1 becomes essential.
- Watch the first 48 hours closely. A flare or two then indifference is fine — that's normal posturing. Relentless chasing, nipping or a tank mate hiding constantly is not.
- Have a backup tank ready. This is non-negotiable. If the betta won't tolerate the community, you need somewhere to move either the betta or the tank mates immediately. Never leave a harried fish "to settle" — it rarely does.
Every betta is an individual, and aggression is partly set during the fish's development rather than something you can train away [3]. If yours flares once and then ignores the corydoras, you've got a community-friendly fish — enjoy it. If he hunts down every tetra you add, that's simply his temperament, and the kind thing is to keep him as a happy single fish. Neither outcome is a failure on your part.
Related reading
For the betta itself — tail types, heater, how to buy one well — start with our betta fish UK buying guide. If you'd rather keep a group than a single male with companions, the rules are completely different: read female betta fish UK before you buy, because females can be grouped where males never can.
Going deeper on the fish themselves? The betta fish care guide covers health, feeding and bubble nests, and the corydoras care guide is the place to get the bottom-dwellers right.
Browse the full range at the betta hub, and find the rest of a peaceful community — tetras, rasboras, shrimp and snails — at the community tank fish hub.
