Flagtail Characin
Semaprochilodus taeniurus
The Flagtail Characin (Semaprochilodus taeniurus) is a peaceful fish that's best left to experienced keepers. Give it a tank of at least 350 litres (92 US gallons), water held at 75-82°F, and a pH of 6-7.5. Always keep a group of at least 5 - they feel safest in numbers.
Captive lifespan reflects typical experience in a home aquarium, not maximum recorded age; genetics, sourcing, and care vary.
Natural distribution
South America
- South America
Regional colours match the stocking calculator's origin map.
Flagtail Characin Tank Setup
A tank of at least 350 litres (92 US gallons) works well. Keep the water at 75-82°F with a pH around 6-7.5, and set up both cover and open swimming space where they spend most of their time (Mid). Always keep a group of at least 5 of their own kind - kept alone or in pairs they tend to turn shy, nippy, or wash out in colour. They reach about 20 cm as adults, so don't be misled by the small juveniles sold in stores.
What Do Flagtail Characins Eat?
They're not fussy eaters - feed a varied diet, rotating good-quality dry, frozen, and gel foods rather than the same thing every day, and match the food size to their mouths.
Flagtail Characin Tank Mates
Grows large; needs very large tank and strong filtration The Flagtail Characin is peaceful, which is the first thing to weigh up when you choose tank mates. At around 20 cm fully grown, it needs tank mates that can hold their own against its size and appetite. It's a shoaling fish, so settle a group of 5 or more of its own kind before adding anything else - a stressed, lonely fish is far more likely to nip or hide. Before you buy, run your full stocking list through our stocking calculator. It weighs temperament, adult size, and water needs together, which a single species page can't do on its own.
Are Flagtail Characins Good for Beginners?
Not a sensible first purchase. Get the tank cycled, keep easier fish stable for a year, then revisit if you still want the extra work this species demands.
Flagtail Characin - frequently asked questions
What size tank do Flagtail Characins need?
Flagtail Characins need a tank of at least 350 litres (92 US gallons). A bigger tank is always easier to keep stable, and gives them more room to settle in and behave naturally.
How many Flagtail Characins should I keep together?
Keep a group of at least 5. Flagtail Characins are a shoaling species and become stressed, lose their colour, or hide when kept singly or in pairs.
What water parameters do Flagtail Characins need?
Keep them at 75-82°F with a pH of 6-7.5, steady rather than chased to an exact figure. In a cycled tank, ammonia and nitrite should both read 0 ppm, with nitrate kept low through regular water changes.
What do Flagtail Characins eat?
Flagtail Characins are omnivores and aren't fussy eaters. Feed a varied mix of good-quality dry, frozen, and gel foods, and match the food size to their mouths. Feed small amounts once or twice a day, and remove anything they don't eat.
Are Flagtail Characins good for beginners?
Flagtail Characins are not a beginner species. They need precise conditions and consistent maintenance, so build experience with hardier fish before keeping them.
Common mistakes with Flagtail Characins
- Buying fewer than 5 - Flagtail Characins need a proper school to feel secure; isolated individuals hide, fail to colour up, or become stressed.
- Underestimating tank size - the minimum footprint is 350 litres (92 US gallons); impulse buying into a smaller tank leads to stress and shortened lifespan.
Building a community? Run the full list through the stocking calculator before you add anything else.
Great tank mates
Chosen from temperament, overlapping temperature/pH bands, plausible minimum tank footprints, and size versus yours in App-aquatic data. Hobby nuance always wins - verify stocking and temperament before purchasing.
Fish to avoid mixing with Flagtail Characins
These well-known species are commonly sold alongside this fish but are not recommended tank mates - verify before purchasing.
- OscarPredator - Oscar will eat or injure smaller tank mates
- Pea PufferPredator - Pea Puffer will eat or injure smaller tank mates
- Betta (Male)Predator - Betta (Male) will eat or injure smaller tank mates
