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Discussion Starter #1 (Edited)
Family: Cobitidae, Subfamily Botiinae

Common Name: Clown Loach

Origin and Habitat: Indonesia, on the islands of Sumatra and Borneo [see comments under Discussion]. Occurs in main river channels, migrating upstream into smaller streams to spawn.

Compatibility/Temperament: Peaceful when maintained as a group in larger aquaria with suitably sized non-aggressive fish such as the larger peaceful barbs, danios, rasbora and cichlids; not recommended with angelfish or discus due to their level of activity. Not a fish for the smaller (under 6 feet) home aquarium. A highly social fish, it must be kept in a group of at least five or six; with fewer than this, subordinate fish of the group will be harassed and other fish in the aquarium may be attacked particularly as the fish matures.

Clown Loach Diet

They are largely carnivorous but will appreciate being fed with vegetable matter such as cucumber, melon and blanched spinach along with frozen bloodworms, shrimps, dried foods, live earthworms. Several aquarists have mentioned that loaches will sometimes eat live plants, with swords (Echinodorus sp) being particular favourites; signs of this will be several small holes eaten in the leaves. Other plant species (crypts, Aponogeton, Anubias, Java Fern) are left alone. Mature clown loaches are well know as plant nibblers. This species in common with many loaches is adept at extracting snails from their shells, but should neve be acquired solely for this purpose. Some fish will lose their timidity and accept hand feeding.


Attains 12 inches on average, though some report 16 inches; between 8 and 12 inches is normal in an aquarium. Growth from the 2 inch size often available in shops to 5 inches is quite rapid so the initial aquarium still needs to be large.

Minimum Tank Suggestion

6 feet in length.

Water parameters for Clown Loach

Soft (< 12 dGH) acidic (pH 5 to 7) water, temperature 25-30C/77-86F. Most fish will still be wild-caught, though the species is now being farmed commercially in SE Asia with hormones.


Clown loach is considered to be the most gregarious of all well-known loaches. It has been the most popular member in the loach family, yet a lot of aquarists fail to realize how large this fish actually grows and few can accommodate their requirements. This fish will live for 20 years if its requirements are met.

An ideal environment would be a 6+ foot tank aquascaped as a river or stream with fine gravel or sand substrate, some smooth rocks and bogwood, and well planted along the back and sides; plants must be sturdy, as this fish will uproot them easily. Hiding places such as caves formed from rock and wood are necessary to provide refuge. Filtration must be good, but not overly strong, or alternatively sufficient "quiet" areas must be available for the fish to rest. The lighting should be subdued, using no more than necessary for the plants and utilizing floating plants to further reduce the light; these fish are somewhat nocturnal and more active in low light.

The fish is intolerant of poor water quality, including high nitrate levels. Regular partial water changes of 50% weekly plus the plants should achieve stable water parameters. This species is highly prone to parasitic (such as ich) and protozoan infestations and poor water conditions are a major factor. Treatment must be carefully monitored, as the fish, like all loaches, is scaleless and thus highly sensitive to any medications or chemicals. Never use salt; and other treatments when necessary should usually be half-strength. Prevention is by far the better.

Typical of most loaches, this species has a clear "pecking order" within the group, dominated by the "alpha" fish, usually a female. Regular scrapes are common, but not serious if the water conditions are maintained properly so the fish heal naturally. The "loach dance" occurs often, and the communication by clicking sounds produced through grinding of the pharyngeal (throat) teeth. When resting, the fish will often tumble over on its side or even back, sometimes under an object; this is natural behaviour, common to many species of loach.

Like all Botiinae species, this one possesses a pair of very sharp spines under the eye sockets; these spines can be extended when the loach feels threatened, and care must be taken not to entangle the spines in nets as it can damage the fish.

When buying clown loaches, please be very observant with their behavior and body structure. You are advised to avoid at all costs clown loaches that appear to have chronic skinny disease. Symptoms will include their obvious skinny appearance where the skull and spinal column are almost visible and concaved stomach. Recommended treatment for this is Levamisole hydrochloride. Ask your local fish store for their sources. This should be applicable to all loaches and more particularly, those that are caught directly from the wild.

Sexual dimorphism is not apparent until spawning season wherein females are often perceived to be taller and rounder in body shape comparative to the males; theories about differences in the caudal fin lobes are inconclusive. Clown loaches do not reach sexual maturity for several years, and reports of successful spawnings in aquaria are infrequent. The fact that the species is a migratory spawner may account for this. These loaches live in the larger river channels and move upstream into smaller streams to spawn during the start of the rainy season in September; the rains cause a significant change to the water parameters and this may trigger the fish into spawning.

There are differences in genetic structure, pattern and mature size between the population on Sumatra and that on Borneo. Further study is needed in order to determine if these are in fact distinct species. For the purposes of the aquarist, externally the pelvic fins of fish from Sumatra are reddish whereas those from Borneo are blackish, sometimes completely black, and the black band on the caudal peduncle terminates closer to the fin on fish from Borneo.

Originally described in 1852 by Pieter Bleeker and named Cobitis macracanthus; Cobitis--the name derived from the Greek kobitis, a type of sardine fish--was erected by Carl Linneaus [the founder of the present binomial nomenclature system used to classify all life] in 1758, and the species epithet macracanthus comes from the Greek macros (= large) and the Latin acanthus (= thorny), a reference to the loach's spine below each eye. It is sometimes seen spelled macracantha [the feminine gender ending] but this is incorrect according to the rules of the ICZN. The species moved to the genus Botia [an Asian word meaning warrior or soldier] in 1989.

In 2004 Dr. Maurice Kottelat divided the 47 species in Botia into seven genera, erecting the new genus Chromobotia [from the Greek chromo meaning colour, and the Asian word botia meaning warrior or soldier] with this species as the type and (to date) only species.

Significant taxonomic revision has been proposed by Kottelat(2004) and Nalbant(2002, 2004) with basic concurrence by Tang (2005) and Slechtova (2006). If adopted, as seems likely, this would raise the subfamily to the rank of family (Botiidae) with seven genera divided between two tribes.


Nalbant, T.T. (2002), "Sixty million years of evolution. Part one: family Botiidae (Pisces: Ostariophysi: Cobitoidea)," Travaux du Museum d'Histoire Naturelle "Grigore Antipa" 44, pp. 309-333.

Kottelat, Maurice (2004), "Botia kubotai, a new species of loach (Teleostei: Cobitidae) from the Ataran River basin (Myanmar), with comments on botiinae nomenclature and diagnosis of a new genus," Zootaxa 401, pp. 1-18.

Tang, Q., B. Xiong, X. Yang and H. Liu (2005), "Phylogeny of the East Asian botiine loaches (Cypriniformes, Botiidae) inferred from mitochondrial cytochrome b gene sequences," Hydrobiologia 544(1), pp. 249-258.

Slechtova, V., J. Bohlen, J. Freyhof and P. Rab (2006), "Molecular phylogeny of the Southeast Asian freshwater fish family Botiidae (Teleostei: Cobitoidea) and the origin of polyploidy in their evolution," Molecular Phylogenetics and Evolution, 39, pp. 529-541.

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