Suitable cardinal tetra tank mates often include peaceful Corydoras, rasboras, small calm cichlids chosen carefully and other non-nippy community fish that share warm soft-to-moderate water. Keep cardinals in a proper school and avoid fish large enough to swallow them. The best community keeps the tetra group intact instead of scattering tank capacity across many single or paired species.
Cardinal tetras are easy to mix behaviourally, but their warm soft-water preference and small adult size are the two main filters for tank-mate choice.
Good companion traits
- Peaceful temperament.
- Compatible warm temperature range.
- Comfort in softer water.
- Adult mouth size too small to treat cardinals as prey.
- No persistent fin-nipping.
School size comes before variety
The RSPCA identifies tetras as shoaling fish and recommends groups of six or more. A strong same-species school is usually better than a collection of isolated community fish.
Small fish can become prey
Even a fish described as peaceful may eat cardinal tetras if it grows large enough. Plan around adult size.
Keep chemistry stable
Avoid combining cardinals with hard-water specialists if doing so forces constant chemical adjustment. Stable suitable water is better than chasing a compromise number.
Related aquarium tools and guides
Frequently asked questions
Can cardinal tetras live with Corydoras?
Often yes when temperature and water chemistry overlap.
Can cardinal tetras live with angelfish?
It carries predation risk because adult angelfish may eat small tetras.
Do cardinals need a school?
Yes. They are shoaling fish and should be kept as a proper group.
Sources and further reading
This guide separates general aquarium arithmetic from fish-welfare decisions. For species-specific limits, always check the needs of the fish you intend to keep.