How long do Cardinal Tetras live?
Cardinals typically live 4-5 years, with 8 years possible in excellent conditions. Wild-caught fish may be older and stressed from collection, so tank-raised stock generally gives you more predictable lifespan.
What do Cardinal Tetras eat?
Feed tiny foods: crushed flake, micro-pellets, and frozen or live baby brine shrimp, daphnia and microworms, once or twice daily in small portions. The usual error is overfeeding and relying on flakes alone, which degrades water and dulls color.
Tank size and water parameters
A 15-20 gallon (57-75 L) tank suits a school of 8-12. Target 73-81°F (23-27°C), pH 4.6-6.5, soft water (low GH), zero ammonia and nitrite, nitrate under 20 ppm. Keep them in groups of 6+; they look best over dark substrate with planted cover and gentle filtration.
Common mistakes with Cardinal Tetras
Biggest errors: dropping them into fresh, hard, alkaline tap water (they want soft acidic water and stable chemistry); keeping them in too small a group; and buying wild-caught fish already weakened by the trade, which raises losses.
Beginner mistakes to avoid
- Putting cardinals in hard, alkaline tap water — they need soft, acidic, stable conditions.
- Adding them to a new tank before it matures — they are far safer in an established aquarium.
- Keeping a small group — a school of 6+ shows the shimmering behavior you bought them for.
- Feeding flakes only and overfeeding — vary the diet and keep portions tiny.