Epalzeorhynchos
Encyclopedia
Epalzeorhynchos is a small ray-finned fish genus
of the family
Cyprinidae. Its members are – like some other cyprinids – known as "freshwater shark
s" or simply "sharks". They are, however, freshwater
members of the Osteichthyes
lineage which is distinct from the Chondrichthyes
lineage of sharks. The description of these animals as "shark" is most likely a reference to the shark-like shape of these popular cyprinids.
The genus Epalzeorhynchos may be placed in the tribe
Garrini of the Labeoninae
, or in subtribe Garraina of tribe Labeonini, if these are considered a tribe of subfamily Cyprininae. It is not yet resolved which is a more appropriate representation of their phylogeny.
be responsible for this similarity. Alternatively, Epalzeorhynchos might be considered a plumper version of Crossocheilus
, which includes the well-known Siamese Algae Eater
(C. siamensis) and is in fact a very close relative. Their coloration is also reminiscent of some Crossocheilus, or of the Mekong loaches (Yasuhikotakia), depending on the particular Epalzeorhynchos species.
Unlike some actual shark
s, which must swim continuously lest they suffocate, Epalzeorhynchos "freshwater shark
s" are Osteichthyes
. Thus, they have gill covers that can actively pump water over the gills, enabling them to breathe comfortably while at rest. As typical for Garrini, they actually spend much time on or near the ground – though not quite as much as the related true gudgeon
s of the Gobioninae or the loach
es of the cypriniform superfamily
Cobitioidea. Still, they usually only move for prolonged distances during migration
to their spawn
ing grounds.
This genus feeds mainly on aufwuchs
, detritus
and small invertebrate
and plant
matter. Their mouthparts are not as apomorphic as that of many other Garrini: they do not have a pronounced rostral cap, but in addition to the two barbel
s on the rostrum
they retain another pair of barbels at the rear edges of the lower maxilla. The upper lip
carries a short bristly ridge, while the lower one has a sizeable hard edge with which they can scrape food off hard substrate
like rocks or logs.
Three species are frequently, the others occasionally found in the aquarium fish
trade. The demand for these colourful fishes is high, and breeding is almost impossible to achieve in the home aquarium. The popular species are thus bred on an industrial scale in Southeast Asia
, but wild-caught fish are sometimes also traded due to a general lack of legal restrictions. This has in some regions drastically reduced stocks, and even led to local extinctions. However, the main problem is dam
ming of rivers between the fishes' usual haunts and the breeding grounds. While otherwise a considerable take of wild Epalzeorhynchus could be sustained, dams will literally stand in the way of successful reproduction, and such isolated subpopulations are easily extinguished by overfishing
. Water pollution
is also problematic. Due to these threats, the Red-tailed Black Shark
(E. bicolor) is very rare and perhaps even extinct in the wild
already – though as it is still bred by fish traders in massive numbers, it is often found in aquaria even today.
are placed in this genus
:
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
of the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
Cyprinidae. Its members are – like some other cyprinids – known as "freshwater shark
Freshwater shark
True freshwater sharks are sharks able to live in freshwater lakes and rivers, including:* the bull shark, Carcharhinus leucas, which swims up tropical rivers around the world...
s" or simply "sharks". They are, however, freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
members of the Osteichthyes
Osteichthyes
Osteichthyes , also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species...
lineage which is distinct from the Chondrichthyes
Chondrichthyes
Chondrichthyes or cartilaginous fishes are jawed fish with paired fins, paired nares, scales, two-chambered hearts, and skeletons made of cartilage rather than bone...
lineage of sharks. The description of these animals as "shark" is most likely a reference to the shark-like shape of these popular cyprinids.
The genus Epalzeorhynchos may be placed in the tribe
Tribe (biology)
In biology, a tribe is a taxonomic rank between family and genus. It is sometimes subdivided into subtribes.Some examples include the tribes: Canini, Acalypheae, Hominini, Bombini, and Antidesmeae.-See also:* Biological classification* Rank...
Garrini of the Labeoninae
Labeoninae
Labeoninae is a doubtfully distinct subfamily of ray-finned fishes in the family Cyprinidae of order Cypriniformes. They inhabit freshwater and are most abundant in the region around southern China. They are a generally very apomorphic group, perhaps the most "advanced" of the Cyprinidae...
, or in subtribe Garraina of tribe Labeonini, if these are considered a tribe of subfamily Cyprininae. It is not yet resolved which is a more appropriate representation of their phylogeny.
Description and ecology
In size and shape Epalzeorhynchos generally resemble the Indian loaches (Botia), which although they are also cypriniforms, are far too distantly related to have anything other than convergent evolutionConvergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...
be responsible for this similarity. Alternatively, Epalzeorhynchos might be considered a plumper version of Crossocheilus
Crossocheilus
Crossocheilus is a genus of cyprinid fish that occur in Asia. There are currently 16 recognized species.-Species:* Crossocheilus atrilimes Kottelat, 2000* Crossocheilus burmanicus Hora, 1936* Crossocheilus caudomaculatus...
, which includes the well-known Siamese Algae Eater
Siamese algae eater
The Siamese algae eater, Crossocheilus oblongus, is a species of freshwater fish in the carp family, Cyprinidae. This bottom-dwelling tropical fish is found in mainland Southeast Asia that includes the Chao Phraya and Mekong basins as well as the Malay Peninsula. Their natural habitats are streams...
(C. siamensis) and is in fact a very close relative. Their coloration is also reminiscent of some Crossocheilus, or of the Mekong loaches (Yasuhikotakia), depending on the particular Epalzeorhynchos species.
Unlike some actual shark
Shark
Sharks are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 420 million years ago....
s, which must swim continuously lest they suffocate, Epalzeorhynchos "freshwater shark
Freshwater shark
True freshwater sharks are sharks able to live in freshwater lakes and rivers, including:* the bull shark, Carcharhinus leucas, which swims up tropical rivers around the world...
s" are Osteichthyes
Osteichthyes
Osteichthyes , also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species...
. Thus, they have gill covers that can actively pump water over the gills, enabling them to breathe comfortably while at rest. As typical for Garrini, they actually spend much time on or near the ground – though not quite as much as the related true gudgeon
Gudgeon (fish)
Gudgeon is a common name for a number of small freshwater fishes of the families Cyprinidae, Eleotridae or Ptereleotridae. Most gudgeons are elongate, bottom-dwelling fish, many of which live in rapids and other fast moving water....
s of the Gobioninae or the loach
Loach
Loach may refer to:* Loaches, fish families in the Cypriniformes:** Cobitidae, the "true" loaches – formerly all loaches were united in this family** Balitoridae, the hillstream loaches – the largest family, closely related to Cobitidae...
es of the cypriniform superfamily
Taxonomic rank
In biological classification, rank is the level in a taxonomic hierarchy. Examples of taxonomic ranks are species, genus, family, and class. Each rank subsumes under it a number of less general categories...
Cobitioidea. Still, they usually only move for prolonged distances during migration
Fish migration
Many types of fish migrate on a regular basis, on time scales ranging from daily to annually or longer, and over distances ranging from a few metres to thousands of kilometres...
to their spawn
Spawn (biology)
Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...
ing grounds.
This genus feeds mainly on aufwuchs
Aufwuchs
Aufwuchs is a term used to cover the small animals and plants that encrust hard substrates, such as rocks, in aquatic environments. The name originated as a German term literally meaning "surface growth" or "overgrowth", and is frequently mis-spelled "awfuchs" or similar due to the unusual "-ufw-"...
, detritus
Detritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
and small invertebrate
Invertebrate
An invertebrate is an animal without a backbone. The group includes 97% of all animal species – all animals except those in the chordate subphylum Vertebrata .Invertebrates form a paraphyletic group...
and plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
matter. Their mouthparts are not as apomorphic as that of many other Garrini: they do not have a pronounced rostral cap, but in addition to the two barbel
Barbel (anatomy)
A barbel on a fish is a slender, whiskerlike tactile organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, sturgeon, the zebrafish and some species of shark...
s on the rostrum
Rostrum (anatomy)
The term rostrum is used for a number of unrelated structures in different groups of animals:*In crustaceans, the rostrum is the forward extension of the carapace in front of the eyes....
they retain another pair of barbels at the rear edges of the lower maxilla. The upper lip
Lip
Lips are a visible body part at the mouth of humans and many animals. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech...
carries a short bristly ridge, while the lower one has a sizeable hard edge with which they can scrape food off hard substrate
Substrate (marine biology)
Stream substrate is the material that rests at the bottom of a stream. There are several classification guides. One is:*Mud – silt and clay.*Sand – Particles between 0.06 and 2 mm in diameter.*Granule – Between 2 and 4 mm in diameter....
like rocks or logs.
Three species are frequently, the others occasionally found in the aquarium fish
Aquarium fish
In fishkeeping, species of aquarium fish vary with the water chemistry of the aquarium.For species of fish found in particular types of aquaria, see:*List of brackish aquarium fish species*List of freshwater aquarium amphibian species...
trade. The demand for these colourful fishes is high, and breeding is almost impossible to achieve in the home aquarium. The popular species are thus bred on an industrial scale in Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...
, but wild-caught fish are sometimes also traded due to a general lack of legal restrictions. This has in some regions drastically reduced stocks, and even led to local extinctions. However, the main problem is dam
Dam
A dam is a barrier that impounds water or underground streams. Dams generally serve the primary purpose of retaining water, while other structures such as floodgates or levees are used to manage or prevent water flow into specific land regions. Hydropower and pumped-storage hydroelectricity are...
ming of rivers between the fishes' usual haunts and the breeding grounds. While otherwise a considerable take of wild Epalzeorhynchus could be sustained, dams will literally stand in the way of successful reproduction, and such isolated subpopulations are easily extinguished by overfishing
Overfishing
Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans....
. Water pollution
Water pollution
Water pollution is the contamination of water bodies . Water pollution occurs when pollutants are discharged directly or indirectly into water bodies without adequate treatment to remove harmful compounds....
is also problematic. Due to these threats, the Red-tailed Black Shark
Red-tailed black shark
The red-tailed black shark , also known as the redtail shark and Labeo bicolor, is a species of freshwater fish in the carp family, Cyprinidae...
(E. bicolor) is very rare and perhaps even extinct in the wild
Extinct in the Wild
Extinct in the Wild is a conservation status assigned to species or lower taxa, the only known living members of which are being kept in captivity or as a naturalized population outside its historic range.-Examples:...
already – though as it is still bred by fish traders in massive numbers, it is often found in aquaria even today.
Species
A mere five speciesSpecies
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
are placed in this genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
:
- †*Extinct in the WildExtinct in the Wild is a conservation status assigned to species or lower taxa, the only known living members of which are being kept in captivity or as a naturalized population outside its historic range.-Examples:...
Epalzeorhynchos bicolor (H. M. SmithHugh McCormick SmithHugh McCormick Smith was an American ichthyologist and administrator in the Bureau of Fisheries.-Biography:...
, 1931) (Red-tailed Black Shark, Redtail Shark, Red-tailed Labeo, Redtail Sharkminnow) - Epalzeorhynchos frenatum (FowlerHenry Weed FowlerHenry Weed Fowler was an American zoologist born in Holmesburg, Pennsylvania.He studied at Stanford University under David Starr Jordan...
, 1934) (Rainbow Shark, Rainbow Sharkminnow) - Epalzeorhynchos kalopterus (BleekerPieter BleekerPieter Bleeker was a Dutch medical doctor and ichthyologist, famous for his work on the fishes of East Asia – Atlas Ichthyologique des Orientales Neerlandaises – which was published 1862–1877....
, 1851) (Flying Fox) - Epalzeorhynchos munensis (H. M. SmithHugh McCormick SmithHugh McCormick Smith was an American ichthyologist and administrator in the Bureau of Fisheries.-Biography:...
, 1934)