If you want a tankmate for a betta and you want it to actually work, corydoras catfish are near the top of the list. They are peaceful, they live on the bottom while the betta patrols the middle and top, they show no interest in the betta's fins or territory, and they bring genuine benefit by foraging leftover food off the substrate. This is a high-confidence pairing — the score of 82 reflects how reliably it succeeds when the basic requirements are met.
The Quick Verdict
Betta plus corydoras is one of the safest community combinations you can build around a betta. The two species barely interact: corydoras are bottom-oriented shoaling catfish with no aggression and no interest in the upper water column the betta defends. The pairing's requirements are about the corydoras' needs (group size, substrate, tank size), not about conflict between the two species.
This works far more reliably than betta and shrimp, because corydoras are too large to be prey and too peaceful to be a threat.
Temperament and Interaction
Bettas are territorial toward things that look like rival bettas or that nip fins — long-finned, brightly coloured, surface-dwelling fish. Corydoras are none of those. They are drab, bottom-hugging, fast-darting catfish that simply go about their business on the substrate. The typical betta either ignores them completely or gives an early half-hearted flare and then loses interest within a day.
Corydoras are also armoured and quick, so even an unusually feisty betta cannot do them harm. The interaction risk in this pairing is genuinely low — the rare failure is an exceptionally aggressive betta, and even then the cories are well equipped to shrug it off.
Water Parameters
Betta and most common corydoras overlap well, with temperature being the main thing to get right.
| Parameter | Betta | Corydoras | Overlap |
|---|---|---|---|
| Temperature | 76–82°F | 72–79°F | 76–79°F |
| pH | 6.5–7.5 | 6.5–7.8 | 6.5–7.5 |
| GH | 3–8 dGH | 2–12 dGH | 3–8 dGH |
| KH | 2–5 dKH | 2–8 dKH | 2–5 dKH |
Aim for around 78°F, which keeps the betta warm enough while staying within the corydoras' comfort range. One note: some corydoras (like the common bronze and peppered) tolerate the cooler end, while a few delicate species prefer it warmer — match the species to the betta's warmth. Confirm your own water with the GH/KH converter.
Tank Size and Setup
The requirements here are really corydoras husbandry, because the cories are the species with needs the betta does not impose:
- Tank size: 15 gallons (57L) or more. Corydoras are active shoalers that need floor space; a betta can live in less, but the cories cannot.
- A group of 6 or more. This is the most-broken rule. Corydoras are shoaling fish and are stressed, shy, and short-lived when kept in ones and twos. Keep at least six of the same species.
- Sand or smooth, rounded substrate. Corydoras forage by sifting substrate through their barbels. Sharp gravel wears down and infects those barbels — sand is strongly preferred.
- Cover and clean water. Plants and hides suit both species, and corydoras appreciate stable, well-filtered water.
Risk Factors
The few things that cause trouble:
- Too few corydoras — a lone or pair of cories is the most common mistake and leads to stressed, hidden, declining fish (not a betta problem, a husbandry one).
- Sharp substrate eroding barbels.
- A tank that is too small or too warm for the chosen corydoras species.
- An exceptionally aggressive betta — rare, and the cories' armour usually handles it, but have a backup plan as always.
- Food competition — make sure sinking food actually reaches the bottom; a greedy betta can intercept it, so feed sinking wafers at lights-out.
How to Make It Work
- Use a 15-gallon-plus tank with sand substrate.
- Add a shoal of at least six corydoras of one species suited to betta-warm water (bronze, peppered, or sterbai for the warm end).
- Provide plants and hides; keep water stable and clean.
- Feed sinking wafers or pellets at night so the cories get their share past the betta.
- Introduce them together or the cories first; watch for the usual brief betta flare that fades within a day.
Both species relish live and frozen foods — corydoras especially benefit from scuds and other meaty live foods that sink and let them forage naturally.
Better or Alternative Tankmates
Corydoras are already one of the best choices, but in the same "peaceful, betta-safe" tier you might also consider otocinclus (algae grazers), kuhli loaches (secretive bottom dwellers), or a nerite snail. For the full ranked list and the reasoning, see the Lab Notes guide on betta tankmates linked below. If you specifically want shrimp, read the more cautious Betta and Shrimp assessment first.
Frequently Asked Questions
Can bettas live with corydoras?
Yes — corydoras are one of the best and safest betta tankmates. They are peaceful bottom-dwelling catfish that occupy a different zone from the betta, show no interest in its territory or fins, and are armoured and quick enough to be safe even from an unusually feisty betta. The main requirements are about the corydoras' needs: a group of six or more, sand substrate, and a tank of 15 gallons or larger.
How many corydoras should I keep with a betta?
At least six of the same species. Corydoras are shoaling fish that become stressed, shy, and short-lived when kept alone or in pairs. A group of six or more lets them behave naturally and stay healthy, which is the single most important factor in this pairing's success.
What tank size do a betta and corydoras need?
A minimum of 15 gallons (about 57 litres). While a betta can live in less, corydoras are active bottom-foragers that need floor space and are kept in groups, so the tank size is driven by their requirements, not the betta's.
Will a betta attack corydoras?
Almost never in a harmful way. A betta may briefly flare at new corydoras but typically loses interest within a day, and corydoras are armoured and fast enough to be unharmed regardless. The interaction risk in this pairing is low; the rare exception is an exceptionally aggressive individual betta, for which a backup plan is wise.
What do corydoras eat in a betta tank?
Corydoras are omnivorous foragers that eat sinking pellets, wafers, and leftover food, along with live and frozen foods like scuds, bloodworms, and daphnia. Because a betta may intercept food at the surface, feed sinking foods at lights-out so the corydoras reliably get their share.
