The rainbow shark (''Epalzeorhynchos frenatum'') is a species of

Southeast Asia Southeast Asia is the geographical United Nations geoscheme for Asia#South-eastern Asia, southeastern region of Asia, consisting of the regions that are situated south of China, east of the Indian subcontinent, and northwest of the Mainland Au ...

n freshwater fish from the family

Cyprinidae Cyprinidae is a family of freshwater fish commonly called the carp or minnow family, including the carps, the true minnows, and their relatives the barbs and barbels, among others. Cyprinidae is the largest and most diverse fish family, and t ...

. It is also known as the ruby shark, red-fin shark, red-finned shark, rainbow sharkminnow, green fringelip labeo, whitefin shark and whitetail sharkminnow.Red-fin Shark, Rainbow Shark, Ruby Shark (''Epalzeorhynchus frenatus''), Mongabay.com, 2006
retrieved on August 17, 2007Rainbow Shark (''Epalzeorhynchos frenatum''), AquariumLife.net (undated)
retrieved on August 17, 2007 It is a popular, semi-aggressive aquarium fish. Unlike true

shark Sharks are a group of elasmobranch cartilaginous fish characterized by a ribless endoskeleton, dermal denticles, five to seven gill slits on each side, and pectoral fins that are not fused to the head. Modern sharks are classified within the ...

s, which belong to the

Chondrichthyes Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeleto ...

("cartilagenous fishes") lineage, the rainbow shark is an

actinopterygii Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class (biology), class of Osteichthyes, bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built ...

an ("ray-finned fish").

Distribution and habitat

Rainbow sharks are native to the basins of

Mekong The Mekong or Mekong River ( , ) is a transboundary river in East Asia and Southeast Asia. It is the world's twelfth-longest river and the third-longest in Asia with an estimated length of and a drainage area of , discharging of wat ...

Chao Phraya The Chao Phraya River is the major river in Thailand, with its low alluvial plain forming the centre of the country. It flows through Bangkok and then into the Gulf of Thailand. Etymology Written evidence of the river being referred to by the ...

, Xe Bangfai and Maeklong in

Indochina Mainland Southeast Asia (historically known as Indochina and the Indochinese Peninsula) is the continental portion of Southeast Asia. It lies east of the Indian subcontinent and south of Mainland China and is bordered by the Indian Ocean to th ...

Epalzeorhynchos frenatum-range IUCN 2025

They live in water with sandy substrates, near the river bottom. This species feeds on algae and plankton, and seasonally migrates into flooded areas, then recedes back to the rivers as the floods dry up.

Description

The rainbow shark has an elongated black, dark blue or bright blue body. 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 long.

Variants

The albino red-fin shark or albino rainbow sharkminnow is a variety of rainbow shark with a white body and red/orange fins.Fenner, Bob. The Rainbow, Redfin and Albino Minnow Sharks, Epalzeorhynchos munense and E. frenatum, The Conscientious Aquarist, WetWebMedia.com (undated)
retrieved on August 17, 2007 It closely resembles "normal" rainbow sharks in temperament and appearance, thus they share the same common names in the aquarium industry.
retrieved on August 17, 2007 These have sometimes been referred to as '' E. munense'', but that is a separate species that rarely enters the aquarium trade. The rainbow shark is also one of the types of genetically modified, fluorescent fish known as

GloFish The GloFish is a patented and trademarked brand of fluorescently colored genetically modified fish, genetically modified aquarium fish. They have been created from several different species of fish: zebrafish were the first GloFish available in ...

Another variant that exists is a rarer form, often referred to as the "ghost sharkminnow". Its appearance is otherwise identical to the typical rainbow shark, however its fins are white, and almost transparent

In the aquarium

Behavior

Rainbow sharks are tank-bottom and aquarium-surface cleaners. Being bottom- and mid-level dwellers, they consume leftover fish food, but also eat the algae growing off surfaces. They are known to be peaceful with their own kind in the wild 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.. A large rainbow shark will continuously chase a smaller one until the smaller one dies, or chase other fish out of its territory, especially in confined environments like aquaria. It may also increase the risk of the fish jumping out of its tank. This makes breeding difficult. The 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 shark The bala shark (''Balantiocheilos melanopterus''), also known as the tricolor shark, tricolor sharkminnow, silver shark, or shark minnow, is a fish of the family Cyprinidae, and is one of the two species in the genus ''Balantiocheilos''. This spe ...

s and black sharks should be avoided, as they will chase and attack them as well.

Tank requirements

An adult rainbow shark thrives in a minimum of 55 gallons of water, with an aquarium length of 48 inches, at the neutral pH range (6 to 8 pH), with temperatures between , and water hardness maintained at 5 to 11 dH. They must have this much space, as they frequently swim around quickly and will terrorize other fish in any tank under this size.

Compatibility

Rainbow sharks are compatible with barbs and

rainbowfish Rainbowfishes are small, colourful freshwater fishes belonging to the Family (biology), family Melanotaeniidae, found in northern and eastern Australia, New Guinea (including islands in Cenderawasih Bay and Raja Ampat Islands in Indonesia), Sula ...

, which are upper- and middle-tank dwellers. They can also live with

danio ''Danio'' is a genus of small freshwater fish in the family (biology), family Cyprinidae found in South Asia, South and Southeast Asia, commonly kept in aquarium, aquaria. They are generally characterised by a pattern of horizontal stripes, rows ...

loaches Loaches are ray-finned fishes of the suborder Cobitoidei. They are freshwater, benthic (bottom-dwelling) fish found in rivers and creeks throughout Eurasia and northern Africa. Loaches are among the most diverse groups of fish; the 1249 known sp ...

, plecos, rasboras, and

gourami Gouramis, or gouramies , are a group of fresh water, freshwater Anabantiformes, anabantiform fish that comprise the family (biology), family Osphronemidae. The fish are native to Asia—from the Indian Subcontinent to Southeast Asia and northeas ...

s. They can be housed with some species of larger freshwater shrimp although any fry or eggs might get eaten by the shark. They are not compatible with smaller, more timid fish in the tank, as the sharks may terrorize them by chasing them from their territory.Rainbow Shark Information, TimsTropicals.com, 2007
retrieved on August 17, 2007

Diet

Rainbow sharks are

omnivore An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize t ...

s that in captivity primarily consume

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

in the form of flakes, but also live foods such as insect

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e, tubifex worms,

periphyton Periphyton is a complex mixture of algae, cyanobacteria, heterotrophic microbes, and detritus that is attached to submerged surfaces in most aquatic ecosystems. The related term Aufwuchs ( German "surface growth" or "overgrowth", ) refers to the ...

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

phytoplankton Phytoplankton () are the autotrophic (self-feeding) components of the plankton community and a key part of ocean and freshwater Aquatic ecosystem, ecosystems. The name comes from the Greek language, Greek words (), meaning 'plant', and (), mea ...

zooplankton Zooplankton are the heterotrophic component of the planktonic community (the " zoo-" prefix comes from ), having to consume other organisms to thrive. Plankton are aquatic organisms that are unable to swim effectively against currents. Consequent ...

and aquatic insects, and

lettuce Lettuce (''Lactuca sativa'') is an annual plant of the family Asteraceae mostly grown as a leaf vegetable. The leaves are most often used raw in Green salad, green salads, although lettuce is also seen in other kinds of food, such as sandwiche ...

and

spinach Spinach (''Spinacia oleracea'') is a leafy green flowering plant native to Central Asia, Central and Western Asia. It is of the order Caryophyllales, family Amaranthaceae, subfamily Chenopodioideae. Its leaves are a common vegetable consumed eit ...

. They will also eat frozen bloodworms and brine shrimp.

Breeding

No actual breed sequence has been documented in an aquarium setting. Although known to be egg-layers, reproduction of rainbow sharks is difficult in an aquarium setting. Large numbers are bred in southeast Asian commercial farms.SeriouslyFish:
Epalzeorhynchos frenatum.
' Retrieved 30 July 2014.

References

External links

* {{DEFAULTSORT:shark, rainbow

rainbow shark The rainbow shark (''Epalzeorhynchos frenatum'') is a species of Southeast Asian freshwater fish from the family Cyprinidae. It is also known as the ruby shark, red-fin shark, red-finned shark, rainbow sharkminnow, green fringelip labeo, whitefin ...

Taxa named by Henry Weed Fowler

Freshwater fish of Southeast Asia