Visual Difference
Neon — red color extends to mid-body, blue line from gill to mid-body.
Cardinal — red color extends from gill to tail base, blue line goes full length.
Size
Neon — smaller (1.5 inches max).
Cardinal — larger (2 inches max).
Hardiness
Neons — generally hardier, more captive-bred populations.
Cardinals — more sensitive, often wild-caught (less hardy due to shipping stress).
Schooling
Both school well in groups of 8-10+.
Cardinal schools are more visually impressive due to extended color.
Compatibility
Both peaceful — perfect for South American community tanks.
Discus love cardinal tetras as tank mates.
- ✦Quarantine new neons especially — Neon Tetra Disease (NTD) is real and fatal
- ✦Soft water (pH 6.0-7.0) brings out best color in both species
- ✦Avoid mixing with fin-nippers — long-fin tetras prefer mild company