The bala shark, ''Balantiocheilos melanopterus'', also known as the tricolor shark, tricolor sharkminnow, silver shark, or shark minnow, is a fish of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Cyprinidae, and is one of the two species in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

'' Balantiocheilos''. This species is not a true

shark Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachi ...

, but is commonly so called because of its

torpedo A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, and with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, s ...

-shaped body and large fins.

Distribution

The bala shark occurs in the Malay Peninsula, Sumatra, and

Borneo Borneo (; id, Kalimantan) is the List of islands by area, third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java Isl ...

. Previous records further north in the

Mekong The Mekong or Mekong River is a trans-boundary river in East Asia and Southeast Asia. It is the world's twelfth longest river and the third longest in Asia. Its estimated length is , and it drains an area of , discharging of water annuall ...

and Chao Phraya River is due to confusion with the recently described and possibly extinct '' B. ambusticauda'' (although the presence of any ''Balantiocheilos'' in the Mekong is questionable).

Appearance and anatomy

These fish have a silver body with black margins on their dorsal,

caudal Caudal may refer to: Anatomy * Caudal (anatomical term) (from Latin ''cauda''; tail), used to describe how close something is to the trailing end of an organism * Caudal artery, the portion of the dorsal aorta of a vertebrate that passes into the ...

, anal, and pelvic fins. They have big eyes to find and catch their prey. The bala shark will grow to a maximum length of .

Habitat and ecology

Bala sharks are found in midwater depths in large and medium-sized rivers and lakes. They feed on

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

, but mostly on small

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean gro ...

s, rotifers, and

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...

s and their

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. Th ...

In the aquarium

Bala sharks are misunderstood aquarium fish. These fish are generally peaceful and good companions to many other types of tropical fish. Bala sharks are widely available in most pet stores, but will grow to a size too large for the home aquarium. They are a hardy fish that will tolerate temperature changes, pH changes, and other factors to which other fish may be sensitive. The water pH should be 6.0–8.0. The preferable

water hardness Hard water is water that has high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of limestone, chalk or gypsum, which are largely made up of calcium and magnesium carbonates, ...

for this species is soft to medium (5.0–12.0

dGH Degrees of general hardness (dGH or °GH) is a unit of water hardness, specifically of general hardness. General hardness is a measure of the concentration of divalent metal ions such as calcium (Ca2+) and magnesium (Mg2+) per volume of water. S ...

). Water temperature should be kept between 22–28 °C (72–82 °F). The bala shark prefers to be kept in groups of two or more specimens. It requires a covered aquarium as it is a skilled jumper, but may injure itself on the lid of the tank. Very young bala sharks are sometimes kept in small aquaria. However, given their adult size, schooling behavior, and swimming speed, the fish quickly grow to need much more room. Hobbyists continue to debate over acceptable minimum tank sizes, but generally recommend at least a 2-meter tank.

FishBase FishBase is a global species database of fish species (specifically finfish). It is the largest and most extensively accessed online database on adult finfish on the web.

lists a minimum of 150 cm (5 ft). Many believe the fish is simply too large and too active to be kept in residential aquaria at all; only enormous, custom-built tanks are acceptable, if any tank at all is. Indoor

pond A pond is an area filled with water, either natural or Artificiality, artificial, that is smaller than a lake. Defining them to be less than in area, less than deep, and with less than 30% Aquatic plant, emergent vegetation helps in disting ...

s are also considered feasible housing options and may be better suited to the average aquarist.

Conservation

''Balantiocheilo melanopterus'' is listed as a

vulnerable species A vulnerable species is a species which has been categorized by the International Union for Conservation of Nature as being threatened with extinction unless the circumstances that are threatening its survival and reproduction improve. Vulne ...

by the

IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...

. It has become rare or extinct in many river basins of its native range. In Danau Sentarum (Borneo), fishermen already reported in 1993 and 1995 that the populations had decreased dramatically after 1975, for no clear reason. Fishermen mentioned

overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in the ...

for the aquarium-fish trade or forest fires in 1975 and the resulting pollution as possible causes. The species is apparently extirpated in the Batang Hari basin ( Sumatra) and it seems that all individuals of ''B. melanopterus'' exported from Indonesia and Thailand by the aquarium-fish trade are captive bred.

References

{{Taxonbar, from=Q187808 Balantiocheilos Fish of Asia Fish of Thailand Freshwater fish of Indonesia Freshwater fish of Malaysia Fishkeeping Fish described in 1850 Taxa named by Pieter Bleeker