| Temperature | 24–28 °C (75–82 °F) |
|---|---|
| pH | 4.5–7.0 |
| Min tank | 10 gal (38 L) |
| Adult size | 5 cm |
| Lifespan | 5–8 years |
A Cardinal tetra is one of those animals that looks simple in the shop bag and turns out to have opinions once it is home. The Paracheirodon axelrodi Cardinal tetra is a long-time favourite for a reason, but it has specific needs that generic "community fish" advice misses.
At a glance
| Minimum tank | 10 gallons (38 L) |
|---|---|
| Temperature | 24 to 28 °C |
| pH range | 4.5 to 7.0 |
| Adult size | 4 to 5 cm |
| Lifespan | 5 to 8 years |
| Group size | a group of 8+ |
Where it comes from
In the wild the Cardinal tetra lives in slow, vegetated waters where cover is everywhere and currents stay gentle. Recreating that means planting densely, keeping the filter flow soft, and avoiding bright, open tanks that leave the fish exposed. Stable water matters more than perfect parameters.
Tank setup
Start with at least 10 gallons and a mature, cycled filter — see the pogostemon helferi guide before you buy. A sand or fine gravel substrate, a few driftwood branches and a carpet or mid-ground plant mass give the fish somewhere to retreat. Keep nitrates under 20 ppm with a weekly 23% water change.
Feeding
Feed a varied diet: a quality flake or micro-pellet as the base, topped up with frozen or live foods two or three times a week. Offer only what the fish clears in about 2 minutes, once or twice daily. Overfeeding is the single most common cause of water-quality swings.
A mistake everyone makes
Adding a Cardinal tetra to a brand-new tank is the classic error. An uncycled tank spikes ammonia to 0.5 ppm within days and the fish pays for it. Cycle first, stock lightly, and let the group size build up gradually.
Good tank mates
Peaceful, similar-sized neighbours work best. Avoid fin-nippers and anything large enough to swallow the Cardinal tetra. A planted community with our light timer guide guide in the mix tends to settle quickly.
If you are new to this species
Start with the minimum 10 gallon tank fully cycled, hold the temperature at 24 to 28 °C, and feed a small amount once or twice a day. Resist adding tank mates in the first two weeks so the Cardinal tetra settles without competition.
