Cardinal Tetra Tank Mates

Because cardinal tetras genuinely need softer, more acidic water than a huge share of common community fish, tankmate selection has to weigh water chemistry compatibility as heavily as temperament and size.

Generally Compatible

Other soft-water South American species like rummy-nose tetras, ember tetras, and German blue rams share genuine water chemistry compatibility alongside peaceful temperament, making these some of the most reliable pairings available for a properly set up soft-water tank. Otocinclus catfish and corydoras catfish (particularly soft-water-tolerant cory species) share both peaceful temperament and reasonable water chemistry overlap. Dwarf shrimp like cherry shrimp tolerate the soft, acidic water cardinals need reasonably well, though extremely low pH can affect shrimp molting in extreme cases.

Proceed With Caution

Neon tetras, while behaviorally near-identical and often housed together, are more hard-water tolerant than cardinals and don't strictly need the same soft, acidic water; a mixed school works acceptably in an intermediate compromise water chemistry but isn't fully optimized for either species. Livebearers (platies, mollies, guppies, swordtails) fundamentally prefer harder, more alkaline water directly opposed to cardinal tetra needs, making genuine long-term co-housing in water optimized for both nearly impossible despite compatible temperament.

Generally Incompatible

Hard-water cichlids like most African rift lake species need water chemistry fundamentally opposed to cardinal tetra requirements. Large or predatory fish of any water chemistry preference will simply eat a fish this small regardless of other compatibility factors.

Compatibility Summary

The most dependable cardinal tetra tankmates are other genuine soft-water South American species; livebearers and hard-water specialists are a poor long-term water-chemistry match despite sometimes-compatible temperament.

See also: Cardinal Tetra Care Guide, Cardinal Tetra Hub.