Red-tailed Black Shark
Epalzeorhynchos bicolor
The Red-tailed Black Shark (Epalzeorhynchos bicolor) is a semi-aggressive fish that's a good step up once you have a little experience. Give it a tank of at least 115 litres (30 US gallons), water held at 68-79°F, and a pH of 6-7.8. Always keep a group of at least 6 - 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
Asia
- East & Southeast Asia
Regional colours match the stocking calculator's origin map.
Red-tailed Black Shark Tank Setup
Treat 115 litres (30 US gallons) as a starting point - big predators need length, strong filtration, and a secure lid. Hold the water at 68-79°F and pH 6-7.8, and assume anything small enough to swallow will eventually be eaten. Always keep a group of at least 6 of their own kind - kept alone or in pairs they tend to turn shy, nippy, or wash out in colour. They reach about 12 cm as adults, so don't be misled by the small juveniles sold in stores.
What Do Red-tailed Black Sharks 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.
Red-tailed Black Shark Tank Mates
Keep in groups of at least 6. May nip fins; avoid with long-finned or slow tankmates. The Red-tailed Black Shark is semi-aggressive, which is the first thing to weigh up when you choose tank mates. It's a known fin-nipper, so avoid bettas, guppies, and other slow, long-finned fish. It's a shoaling fish, so settle a group of 6 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 Red-tailed Black Sharks Good for Beginners?
Doable once you test water regularly and catch problems before fish look sick. If this is your first tank, pick something more forgiving and come back later.
Red-tailed Black Shark - frequently asked questions
What size tank do Red-tailed Black Sharks need?
Red-tailed Black Sharks need a tank of at least 115 litres (30 US gallons). A bigger tank is always easier to keep stable, and gives them more room to settle in and behave naturally.
How many Red-tailed Black Sharks should I keep together?
Keep a group of at least 6. Red-tailed Black Sharks are a shoaling species and become stressed, lose their colour, or hide when kept singly or in pairs.
What water parameters do Red-tailed Black Sharks need?
Keep them at 68-79°F with a pH of 6-7.8, 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 Red-tailed Black Sharks eat?
Red-tailed Black Sharks 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 Red-tailed Black Sharks good for beginners?
Red-tailed Black Sharks are best for keepers with a little experience. They are manageable once you test water regularly and catch problems early; a complete beginner may prefer something more forgiving first.
Common mistakes with Red-tailed Black Sharks
- Buying fewer than 6 - Red-tailed Black Sharks need a proper school to feel secure; isolated individuals hide, fail to colour up, or become stressed.
- Underestimating tank size - the minimum footprint is 115 litres (30 US gallons); impulse buying into a smaller tank leads to stress and shortened lifespan.
- Mixing with long-finned fish - Red-tailed Black Sharks will nip at bettas, angelfish, and other fish with flowing fins, causing stress and infection risk.
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 Red-tailed Black Sharks
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
