Rainbow shark

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Rainbow shark, red-finned shark, ruby shark
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Cypriniformes
Family: Cyprinidae
Genus: Epalzeorhynchos
Species: E. frenatum
Binomial name
Epalzeorhynchos frenatum
(Fowler, 1934)
  • Labeo frenatus
  • Epalzeorhynchus frenatus
  • Epalzeorhynchos frenatus
  • Labeo munensis
  • Labeo erythrurus
  • Epalzeorhynchos munense

The rainbow shark (Epalzeorhynchos frenatum) is a species of Southeast Asian freshwater fish from the Cyprinidae family.[1] It is a popular, semi-aggressive aquarium fish. It is also variously known as the ruby shark, red-fin shark, red-finned shark, rainbow sharkminnow, green fringelip labeo, whitefin shark and whitetail sharkminnow.[2][3][4] Unlike true sharks, which belong to the Chondrichthyes ("cartilagenous fishes") lineage, the rainbow shark is an actinopterygiian ("ray-finned fish").

Physical description[edit]

The rainbow shark has an elongated, dark-black and greenish body, or also can have a light-orange body with dark-red fins. It also occur in an albino variety, with a white body and bright-orange fins.[5] The snout is pointed. The abdominal area is flat. The fins possess red to orange-red coloration. The linear area from the gill cover, the eye, and the mouth has a characteristic brief stripe. Compared to females, male rainbow sharks have thinner bodies with black lines along the tailfins. Males also have brighter coloration. They can grow up to about 6 in (15 cm) long with an average life span ranging from 4 to 6 years.[2][3][4]

Distribution and habitat[edit]

Rainbow sharks are native to the basins of Mekong, Chao Phraya, Xe Bangfai and Maeklong in Indochina.[1] They live in water with sandy bottoms.[1]

In the aquarium[edit]


Rainbow sharks are tank-bottom and aquarium-surface cleaners. Being bottom- and mid-level dwellers, they consume leftover fish food. They are known to be peaceful with their own kind in nature, but have been known to be aggressive with one another if kept together in a tank. Threat displays and fighting are likely to occur. This fighting behavior involves head-and-tail butting, and also biting.[citation needed]. A large rainbow shark will continuously chase a smaller one until the smaller one dies, especially in confined environments like aquaria. It may also increase the risk of the fish jumping out of its tank. This makes breeding difficult. Provision of hiding places and hollowed decors such as plants or artificial cave-like and tunnel-like aquatic ornaments minimize this typical behavior. Due to this behavioral characteristic among its own kind, rainbow sharks are not recommendable to the new aquarist. Keeping them with relatives, such as red-tailed sharks, bala sharks and black sharks should be avoided.[2][3][4]

Tank requirements[edit]

An adult rainbow shark thrives in a 55-gallon (minimum 30-gal) tank with water at the neutral pH range (6.5 to 7.0 pH), with temperatures between 22 and 26 °C (72 and 79 °F), and water hardness maintained at 2 to 15 dH. They must have this much space, as they frequently swim around quickly and will terrorize other fish in any tank under this size.[2][3][5]


Rainbow sharks are also compatible with barbs and rainbowfish, which are upper- and middle-tank dwellers. They can also live with danios, loaches, plecos, rasboras, and gouramis.[2][3][5]


Rainbow sharks are not picky herbivorous and omnivorous eaters, but are primarily consumers of algae in the form of tablets, wafers and flakes. They also eat live food, such as insect larvae, tubifex worms, periphyton, crustaceans, phytoplankton, zooplankton and aquatic insects. Diet also include lettuce and spinach.[2][4] They will also eat frozen bloodworms and brine shrimp.


No actual breed sequence has been documented. Although known to be egg-layers, reproduction of rainbow sharks is difficult in an aquarium setting.[2][6]


The albino red-fin shark (Epalzeorhynchos munense) or albino rainbow sharkminnow, is a variety of rainbow shark with a white body and red fins.[2][7] The Epalzeorhynchos munense closely resemble Epalzeorhynchos frenatum in temperament and appearance, thus they share the same common names in the aquarium industry.[8]