Cardinal Tetra
Cardinal Tetra
Cardinal Tetra (Paracheirodon axelrodi) is the larger and more vivid sibling of the Neon Tetra — distinguished by its full-length red belly stripe running the entire body from chin to tail, compared to the Neon's half-belly red. Named for Dr. Herbert Axelrod, it has become one of the most important conservation fish in the hobby through Project Piaba — a Brazilian initiative whose motto is 'buy a fish, save a tree.'
Feeding & Care Tip: Hikari Micro Pellets (crushed or soaked briefly) and Sera Vipan Baby make excellent daily staples. Supplement 2–3× per week with Hikari Frozen or Freeze-Dried Baby Brine Shrimp and Hikari Frozen Daphnia. Feed small amounts 2–3 times daily in a calm environment.
Native to the Rio Negro and Rio Orinoco drainages — the Rio Negro being one of the most tannin-rich, acidic river systems on Earth, with pH values often between 4.0 and 5.0 in the wild. Cardinal Tetras are one of the few aquarium fish still primarily wild-caught. Project Piaba has demonstrated that sustainable wild collection provides income for riverside communities while creating economic incentive to preserve Amazon rainforest intact.
Tank-raised specimens adapt well to pH up to 7.0. More sensitive to water quality fluctuations than the hardier Neon Tetra — a mature, stable aquarium is important.
Keep in groups of at least 8 — 15 or more produce the famous tight schooling and maximum color intensity. The full-length red belly distinguishes them from Neon Tetras even across a room.
Care & Ideal Parameters
| Difficulty | Easy — Moderate |
| Temperament | Peaceful — schooling community |
| Typical Adult Size | 1.75 inches (4.5 cm) |
| Min. Group Size | 8 minimum — 15+ for best schooling |
| Ideal Temp | 73–81°F (23–27°C) |
| Ideal pH | 6.0–7.0 |
| Ideal GH | 1–8 dGH |
| Ideal KH | 0–4 dKH |
| Staple Food | Hikari Micro Pellets (crushed/soaked); Sera Vipan Baby |
| Treat / Supplement | Hikari Frozen or Freeze-Dried Baby Brine Shrimp; Hikari Frozen Daphnia |
| Origin | Rio Negro and Rio Orinoco drainages, Brazil, Colombia, Venezuela |
| Notes | Full-length red belly (vs half-belly of Neon Tetra). Named for Dr. Herbert Axelrod. Project Piaba — 'buy a fish, save a tree.' Primarily wild-caught. More sensitive to water quality than Neon Tetra. |
