The clown loach (''Chromobotia macracanthus''), or tiger botia, is a

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

freshwater

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

belonging to the botiid loach family. It is the sole member of the genus ''Chromobotia''. It originates in inland waters in Indonesia on the islands of Sumatra and

Borneo Borneo (; id, Kalimantan) is the 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, west of Sulawesi, and ea ...

. In Sentarum, West Borneo that fish named: ulanguli. It is a popular fish in the freshwater aquarium trade and is sold worldwide.

Taxonomy and naming

The fish was first described as ''Cobitis macracanthus'' by

Pieter Bleeker Pieter Bleeker (10 July 1819 – 24 January 1878) was a Dutch medical doctor, ichthyologist, and herpetologist. He was famous for the ''Atlas Ichthyologique des Indes Orientales Néêrlandaises'', his monumental work on the fishes of East Asia ...

in 1852. In 1989, its scientific name was changed to ''Botia macracanthus''. In 2004, Dr. Maurice Kottelat divided the genus '' Botia'', containing 47 different species, into seven separate genera, resulting in the clown loach being placed in a genus of its own, ''Chromobotia''. Its scientific name roughly translates to “Large-thorned colourful warrior”. The common name, "clown loach" comes from the fish's bright colours and stripes (often tropical fish with stripes that stand out are commonly called "clown") as well as from its habit of 'entertaining' aquarium owners with strange habits, such as swimming upside down, or 'playing dead.'

Description and behavior

Information about the maximum size of the clown loach varies, with some estimates ranging up to , and with typical adult sizes ranging from . The fish's body is long and laterally compressed, with an arched

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage * Dorsal c ...

surface and a flat

ventral Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

surface. Its head is relatively large and its mouth faces downward with thick, fleshy lips, and four pairs of

barbels In fish anatomy and turtle anatomy, a barbel is a slender, whiskerlike sensory organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the zebrafish, the black dragonfish and some s ...

. The

barbel Barbel may refer to: *Barbel (anatomy), a whisker-like organ near the mouth found in some fish (notably catfish, loaches and cyprinids) and turtles *Barbel (fish), a common name for certain species of fish **''Barbus barbus'', a species of cyprinid ...

s on the lower jaw are small and difficult to see. Clown loaches can make clicking sounds when they are happy, being territorial (used as a type of weapon/warning) or mating. This sound is produced by the grinding of their

pharyngeal teeth Pharyngeal teeth are teeth in the pharyngeal arch of the throat of cyprinids, suckers, and a number of other fish species otherwise lacking teeth.dorsal fin A dorsal fin is a fin located on the back of most marine and freshwater vertebrates within various taxa of the animal kingdom. Many species of animals possessing dorsal fins are not particularly closely related to each other, though through c ...

, and wraps around to the ventral surface, and the posterior band covers almost all of the

caudal peduncle Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as see ...

and extends to the anal fin. There is some regional colour variation within the species; the pelvic fins on fish from

are reddish-orange and black, while the pelvic fins on fish from Sumatra are entirely reddish-orange. The fish is sexually dimorphic, with females being slightly plumper than males. In addition, the tips of the tail on the male curve inwards slightly, whereas the females have straight tips. The fish has a movable spine that lies in a groove below the eye, which may be extended as a defence mechanism. The spine may cause a painful wound, but is not venomous. It also may be used as a predation tool as it is set close to the mouth.

Distribution and habitat

Clown loaches are native to the islands of Sumatra and

Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...

. Clear stream environments provide the optimal habitat for clown loaches, but biannual monsoon flooding forces the fish to move into flooded flood plains, or murky or blackwater rivers or lakes, for 7–8 months of the year, and clown loaches are commonly found in the flood plains of hilly areas. Breeding adults migrate to smaller waterways to spawn annually. In its native habitat, the fish is found in water with a temperature range of , a pH between 5.0 and 8.0, and water hardness between 5 and 12 dH.

Reproduction in captivity

Clown loach reproduce in captivity only after hormonal stimulation of final oocyte maturation and ovulation. Captive breeding and mass production of clown loach is done primarily in country of origin (Indonesia) and in Europe ( https://www.youtube.com/watch?v=qerHElt1ozQ ).

In the aquarium

A common and popular fish for tropical freshwater aquaria, ''C. macracanthus'' is a visually pleasing species. Although specimens in the wild will reach 40 to 50 cm, in the aquaria it is uncommon for ''C. macracanthus'' to attain more than 15 to 20 cm fork length. They are a very long-lived species, living up to 30 years. These fish have bifurcated spines under the eyes. They are thought to be used as a defence mechanism and possibly, for obtaining prey. ''C. macracanthus'' will associate with other benthic species in the aquaria if kept singly or with few other specimens. They make suitable tank-mates for any non-aggressive community fishes, but do not thrive when kept with larger, more dominant species. Occasionally ''C. macracanthus'' will exhibit erratic swimming patterns, such as swimming on their sides or upside down. This is not usually a sign of illness, however, and the fish will normally return to normal behaviour almost instantly. As ''C. macracanthus'' is found in riverine environments it is able to cope with good flow rates of water in the aquaria. Aquascapes may replicate this environment to suit the requirements of the species with areas of high flow, but also typically include areas of low flow to allow the fish to rest. ''C. macracanthus'' is also fond of cover and is not overly accustomed to bright lighting. The fish will often seek areas of shade or cover in which to rest during the day and become more active when light levels are more subdued. The barbels of clown loaches are known to be easily damaged by rough substrates, such as gravel, in aquaria. Clown loaches are particularly susceptible to Ichthyophthirius (ich), or white spot disease. Due to the fact that clown loaches have small or no scales, they are often not treated with full doses of medications. Over-exploitation of ''C. macracanthus'' has motivated the development of conservation efforts, mostly new artificial propagation techniques. ''C. macracanthus'' is easier to breed when individuals are between two and four centimeters in size. Most clown loaches accept commercial flake food and sinking pellets as their dietary staple, but thrive with a variety of food: live (worms, brine shrimp, small snails), banana, other plant matter, freeze-dried ( tubifex worms, especially if it is fortified) and frozen

brine shrimp ''Artemia'' is a genus of aquatic crustaceans also known as brine shrimp. It is the only genus in the family Artemiidae. The first historical record of the existence of ''Artemia'' dates back to the first half of the 10th century AD from Urmia L ...

. Clown loaches (and their cousins) are also one of the few fishes that will eat bladder snails (''

Physella acuta ''Physella acuta'' is a species of small, left-handed or sinistral, air-breathing freshwater snail, an aquatic gastropod mollusk in the family Physidae. Common names include European physa, tadpole snail, bladder snail, and acute bladder snail ...

''), and are valued by aquarists for controlling this pest in planted aquaria.

References