Can Cardinal tetra Live With Congo tetra?

Detailed assessment

Both Cardinal tetra and Congo tetra share a comfortable temperature range of 23–28°C (Cardinal tetra prefers 23–29°C, Congo tetra prefers 23–28°C). Their pH ranges overlap well at 6–7.5, so water chemistry is compatible. Both species have low aggression scores (Cardinal tetra: 1, Congo tetra: 1 out of 5), which supports peaceful cohabitation. The size difference is significant: Congo tetra reaches 8 cm while Cardinal tetra reaches only 3.5 cm, and the larger species may view the smaller one as prey. Note: fish 2x+ larger may eat smaller tankmates. With careful monitoring and adequate tank size these species can usually coexist, but be prepared to separate them if aggression or stress appears.