Sailfin Tetra
Sailfin Tetra
Sailfin Tetra (Crenuchus spilurus) is a fascinating and unusual characin — not a true tetra but a member of the family Crenuchidae, the South American darters. Adult males develop an extraordinarily tall, sail-like dorsal fin — the most dramatic fin development of any fish its size. Behavior is more similar to a dwarf cichlid than a schooling tetra.
Feeding & Care Tip: Hikari Micro Pellets (crushed or soaked) 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 blackwater streams of the upper Amazon and Orinoco basins. Males establish and defend territories and form loose harems with females. The sail dorsal fin is used in threat displays and courtship.
Keep as one male with multiple females — males fight persistently together in small tanks. Not a true schooling fish. Peaceful with other small species that don't compete for territory. Blackwater conditions with tannin additions produce best color.
A specialist fish for blackwater aquarists. The male's sail dorsal fin rivals any betta fin in dramatic development — one of the most extraordinary fin structures in freshwater fish.
Care & Ideal Parameters
| Difficulty | Moderate |
| Temperament | Males territorial — not a schooling fish |
| Typical Adult Size | 2.5 inches (6.3 cm) |
| Min. Group Size | 1 male + 2–3 females |
| Ideal Temp | 73–82°F (23–28°C) |
| Ideal pH | 5.0–6.8 |
| Ideal GH | 0–6 dGH |
| Ideal KH | 0–3 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 | Upper Amazon and Orinoco blackwater streams, Brazil and Venezuela |
| Notes | Family Crenuchidae — not Characidae. Males have extraordinary tall sail dorsal fin. Territory-holding, not schooling. Behavior like dwarf cichlid. |
