Yes: Compatible.
No clashes under our rules: they share a temperature range, neither is a fin nipper or predator of the other, and their temperaments fit.
Temperature. Bronze corydoras does best at 21–25 °C (70–77 °F) and Cardinal tetra at 23–27 °C (73–81 °F). They share 23–25 °C.
Water. Their pH ranges overlap at 6–6.
Temperament and size. Bronze corydoras is peaceful and grows to 7.5 cm; Cardinal tetra is peaceful and grows to 3.5 cm. Bronze corydoras swims at the bottom and Cardinal tetra at the mid, which spreads them out.
Tank size and groups. Plan on at least 20 US gallons, the larger of the two cautious minimums. Keep Bronze corydoras in a group of 6+. Keep Cardinal tetra in a group of 8+. A starter mix of 6 Bronze corydoras and 8 Cardinal tetra in 20 gallons uses about 110% of the tank’s bioload capacity under our rules and grades A.
Keeping them together
- Feeding: Bronze corydoras feeds on the bottom. Add sinking pellets or wafers after lights-out so faster mid-water fish don’t take it all.
- Aquascape: both are calmer with cover. Plants and floating cover make shy fish come out more, not less.
- Group size: a full group is not optional. A schooling fish kept in too small a group is stressed and more likely to nip or hide.
- Adding them: add the calmer species first and let it settle for a week or two before adding the other, and only once your tank has cycled.
Open this pair in the checker Add your other fish to grade the whole tank.
Quick facts
| Bronze corydoras | Cardinal tetra | |
|---|---|---|
| Adult size | 7.5 cm | 3.5 cm |
| Min tank | 20 gal | 20 gal |
| Temperature | 21–25 °C | 23–27 °C |
| pH | 6–7 | 4.6–6 |
| Temperament | peaceful | peaceful |
| Group size | 6+ | 8+ |
Data from the Species Ledger, checked November 9, 2026, with at least two sources per species. Cautious community guidelines, not guarantees: individual fish vary. Not veterinary advice. Disagree? Tell us.