Rainbow Shark
Epalzeorhynchos frenatum
Also known as: Ruby shark, Red-finned shark, Rainbow sharkminnow
Quick Facts
- Adult size: 12-15 cm (4.7-5.9 inches)
- Minimum tank size: 110 litres (29 gallons)
- Lifespan: 5–8 years
- Temperament: semi-aggressive
- Swimming level: bottom
- Diet: omnivore
- Minimum group size: 1
- Difficulty: intermediate
Water Parameters
- Temperature: 24–28°C
- pH: 6.5–7.8
- Hardness (GH): 89–268 ppm (5–15 dGH)
Values above are general hardness (GH). For carbonate hardness (KH), the buffer that keeps pH stable, see the water parameters guide.
Care Summary
A sleek, dark-bodied fish with vivid red-orange fins, sold as a hardy and striking centrepiece, which it is, provided its territoriality is respected. Despite the name it is not a shark but a member of the carp family, a bottom-oriented fish that claims and patrols a territory on the substrate. Juveniles are often peaceable, but as they mature they grow assertive, particularly toward their own kind and other floor-dwellers, which is the source of most stocking trouble. One per tank, plenty of space, and fast upper-water companions are the recipe for success. An albino strain is widely sold and behaves identically. Hardy and long-lived, and an excellent single-specimen feature fish for a robust community of the right size.
Tankmates
Keep one, and only one, per tank: rainbow sharks are territorial toward their own kind and toward the very similar red-tailed black shark, and two in anything but a very large, broken-up tank means relentless chasing and a dead subordinate. They are territorial toward other bottom-dwellers too, so corydoras, loaches, and other plecos in their floor space get harassed. The right tankmates are fast, mid-to-upper-water fish that stay out of the shark's zone: danios, larger barbs, rainbowfish, and congo tetras. Provide caves and broken sightlines to give the shark a territory and the others escape routes. Will eat dwarf shrimp, and aggression escalates as the fish matures.
Compatible with
Avoid keeping with
- Betta
- Bronze Corydoras
- Bristlenose Pleco
- Kuhli Loach
- Cherry Shrimp
- Clown Loach
- Red-Tailed Black Shark
Common Problems
- territorial aggression toward bottom-dwellers and its own kind
- fighting if more than one is kept
- increasing assertiveness with age
- ich
Sources: seriouslyfish.com, fishbase.org · Last updated: 2026-06-20