Red-tailed black shark
Epalzeorhynchos bicolor
A velvet-black 'shark' with a red tail; beautiful but territorial, chasing lookalike bottom fish and its own kind as it ages.
Key facts
- Body length
- 4.9 in without fins
- Minimum tank
- 76 gallons
- Group
- Alone is fine
- Temperament
- Aggressive
- Care level
- 3 / 5
- Lifespan
- 15+ years
- Diet
- Algae wafers, vegetables, sinking pellets, frozen bloodworm
- Origin
- Central Thailand (Mae Klong and Chao Phraya basins)
- Hardier than32%
- Bigger than66%
- Calmer than14%
Water: their range vs yours
Red-tailed black shark tank mates
- BettaGets along in shared water.Good mates
- AngelfishGets along in shared water.Good mates
- Blood parrot cichlidGets along in shared water.Good mates
- Common plecoGets along in shared water.Good mates
- Dwarf gouramiGets along in shared water.Good mates
- Leopard sailfin plecoGets along in shared water.Good mates
- SeverumGets along in shared water.Good mates
- Three spot gouramiGets along in shared water.Good mates
- Assassin snailGets along in shared water.Good mates
- Red swamp crayfishGets along in shared water.Good mates
- Redclaw crayfishGets along in shared water.Good mates
- Elephantnose fishGets along in shared water.Good mates
- Neon tetraRed-tailed black shark attacks fish with a similar shape or colour: Neon tetra.Risky
- Harlequin rasboraRed-tailed black shark attacks fish with a similar shape or colour: Harlequin rasbora.Risky
- Fancy guppyRed-tailed black shark attacks fish with a similar shape or colour: Fancy guppy.Risky
- Panda corydorasRed-tailed black shark (aggressive) will bully the peaceful Panda corydoras.Risky
- OtocinclusRed-tailed black shark (aggressive) will bully the peaceful Otocinclus.Risky
- Cherry shrimpRed-tailed black shark (aggressive) will bully the peaceful Cherry shrimp.Risky
- Chinese algae eaterTwo territorial lookalikes clash.Avoid
- Iridescent sharkIridescent shark can eat Red-tailed black shark: prey body depth 2.8 cm ≤ mouth 32.5 cm.Avoid
- OscarOscar can eat Red-tailed black shark: prey body depth 2.8 cm ≤ mouth 12.3 cm.Avoid
- Rainbow sharkSharks fight lookalike sharks.Avoid
- Siamese algae eaterAttacks lookalike algae eaters.Avoid
- African clawed frogAfrican clawed frog should only be kept in a single-species tank.Avoid
How we check
The numbers the tank model uses for red-tailed black sharks: water as ideal and tolerated ranges, bioload from adult mass, space, flow and how they act on other species.
- Standard length
- 12.5 cm (SL)
- Adult mass
- 42.55 g
- Bioload at 25 °C
- 10.92 BU
- Min. water
- 243 L net
- Min. footprint
- 120 × 45 cm per specimen
- Group
- 1+ (best 1)
- Swims in
- bottom, middle
- Flow
- moderate
- Body / fins
- fusiform, normal fins
- Diet type
- omnivore plant
- Fin nipper
- none
- Sensitive to
- nitrate
Sources: Seriously Fish: Epalzeorhynchos bicolor · FishBase: Epalzeorhynchos bicolor
Care notes
Red-tailed black sharks come from rivers of central Thailand, where they were once declared extinct and remain critically endangered; all fish on sale are farmed. They can live more than 15 years.
Keep one per tank, about 55 gallons with a 4 by 1.5 foot footprint, and add it last. It is aggressive toward other sharks, Siamese algae eaters and Chinese algae eaters; catfish and cichlids are best avoided too.
Questions
What size tank does a red-tailed black shark need?
At least 76 gallons (243 litres of water after decor). Adults reach about 4.9 inches without fins.
How many red-tailed black sharks should be kept together?
One is fine. They do not need company of their own kind.
What water do red-tailed black sharks need?
72–79 °F, pH 6.5–7.5 and 2–15 dGH. Red-tailed black sharks come from Central Thailand (Mae Klong and Chao Phraya basins).
How long do red-tailed black sharks live?
15+ years with good care.
What fish can live with red-tailed black sharks?
Good tank mates include Betta, Angelfish, Blood parrot cichlid, Common pleco and Dwarf gourami. Each is checked both ways for size, fin nipping, temperament, territory and shared water.