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. Guppy does best at 18–28 °C (64–82 °F) and Pygmy corydoras at 22–26 °C (72–79 °F). They share 22–26 °C.
Water. Their pH ranges overlap at 7–7.4.
Temperament and size. Guppy is peaceful and grows to 6 cm; Pygmy corydoras is peaceful and grows to 3 cm. Guppy swims at the top and Pygmy corydoras at the mid, which spreads them out.
Tank size and groups. Plan on at least 10 US gallons, the larger of the two cautious minimums. Keep Guppy in a group of 3+. Keep Pygmy corydoras in a group of 6+. A starter mix of 3 Guppy and 6 Pygmy corydoras in 10 gallons uses about 94% of the tank’s bioload capacity under our rules and grades A.
Keeping them together
- Feeding: both feed in open water. Feed small amounts two or three times a day so the slower eater gets its share.
- 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.
- Shrimp and snails: neither is a known invertebrate eater, but baby shrimp can still be eaten. Dense moss helps.
- 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
| Guppy | Pygmy corydoras | |
|---|---|---|
| Adult size | 6 cm | 3 cm |
| Min tank | 10 gal | 10 gal |
| Temperature | 18–28 °C | 22–26 °C |
| pH | 7–8 | 6.4–7.4 |
| Temperament | peaceful | peaceful |
| Group size | 3+ | 6+ |
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.