Cardinal Tetra and Swordtail: Can They Live Together?
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Side-by-side comparison
| Factor | Cardinal Tetra | Swordtail | Assessment |
|---|---|---|---|
| Water temperature | 73–81°F | 72–82°F | Overlap 73–81°F |
| pH | 5.5–7 | 7–8.4 | Tight overlap |
| Hardness | 1–8 dGH | 12–30 dGH | No overlap |
| Adult size | 2.0″ | 5.5″ | 2.8× difference |
| Temperament | Peaceful | Peaceful | Both peaceful |
| Swim level | Mid | Mid | Same zone |
| Minimum tank | 20 gal | 20 gal | Together: 32 gal+ |
Shared water parameters
- Temperature both tolerate: 73–81°F
- pH both tolerate: 7–7
- No shared hardness window.
- Recommended combined tank: 32 gallons or larger
Risks and things to watch
Both occupy the mid zone
Competition for space and food is higher when two species share the same layer. Increase footprint rather than height.
Group requirements
Compatibility is not only about the two species getting along — each still needs its own social setup met inside the same tank.
- Cardinal Tetra — minimum group of 6. Budget tank space for the whole shoal, not one fish.
- Swordtail — minimum group of 3. Budget tank space for the whole shoal, not one fish.
Frequently asked questions
Can cardinal tetra and swordtail live together?
Yes — compatible. Cardinal Tetra and Swordtail are a good match. They share a workable temperature and pH window, neither is large enough to threaten the other, and temperaments are compatible. Give them at least 32 gallons once both group requirements are met.
What size tank do cardinal tetra and swordtail need together?
Plan for at least 32 gallons. Cardinal Tetra alone needs 20 gallons and Swordtail needs 20, but combined stocking needs headroom for filtration and swimming space, not just volume.
What temperature suits both species?
Both are comfortable between 73 and 81°F. Set the heater to the middle of that window and keep it stable.
What pH works for both?
Aim for pH 7–7, which sits inside both species' comfortable range.
Will swordtail eat cardinal tetra?
Unlikely. At 5.5″ versus 2.0″ the size gap is not large enough for predation, though fry and juveniles are never safe in a community tank.
How should the tank be arranged?
Use plants, wood and rock to break sight lines, keep open swimming space along the front, and add the more territorial species last so it cannot claim the whole tank before the other settles in.
Explore further
Assessment generated from our compatibility methodology: parameter overlap, adult size ratio, temperament and swimming zone. Reviewed by Marcus Rivera.