Clown loach

Clown loach
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Actinopterygii
Order:	Cypriniformes
Family:	Cobitidae
Genus:	Chromobotia
Species:	C. macracanthus
Binomial name
Chromobotia macracanthus (Bleeker, 1852)

The clown loach, Chromobotia macracanthus, is a tropical freshwater fish belonging to the Cobitidae (loach) family. It is the sole member of the Chromobotia genus. It originates in inland waters in Indonesia on the islands of Sumatra and Borneo. 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 in 1852. In 1989, the scientific name was changed to Botia macracanthus. In 2004, Dr. Maurice Kottelat split the Botia genus, containing 47 different species, into seven separate genera, resulting in the clown loach being placed into a genus of its own, Chromobotia.

The genus Chromobotia derives its name from the Greek word chromo, meaning "colour", and the regional Asian word botia, meaning "warrior" or "soldier". The specific epithet macracanthus is derived from the Greek word macros, meaning "large" and the Latin word acanthus, meaning "thorny", referring to the large spines below the fish's eyes. The "Clown loach" common name comes from the fish's bright colors resembling a clown's makeup, and the fish's ability to entertain observers with its comical behavior when kept in an aquarium.

Description and behavior

Information about the maximum size of the clown loach varies, with some estimates ranging from 11 to 14 inches (40 to 50 cm), and with typical adult sizes ranging from 7 to 10 inches (15 to 20 cm). The fish's body is long and laterally compressed, with an arched dorsal surface and a flat ventral surface. Its head is large and its mouth faces downward with thick, fleshy lips, and four pairs of barbels. The barbels on the lower jaw are small and difficult to see.

The body is whitish-orange to reddish-orange, with three thick, black, vertical bands. The first band runs from the top of the head and through the eye. The second band lies between the head and the dorsal fin, and wraps around to the belly, and the third band covers the start of the caudal peduncle and extends to the anal fin. There is some regional color variation in the species; the pelvic fins on fish from Borneo 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 defense mechanism. The spine may cause a painful wound, but is not venomous.

Distribution and habitat

Clown loaches originate in Indonesia, on the islands of Sumatra and Borneo. For the greater part of the year, the fish lives in murky or blackwater rivers and lakes, but breeding adults migrate to smaller waterways to spawn annually. They are especially predominant in the flood plains of the hill country.

In its native habitat, the fish is found in water with a temperature range of 77 to 86 °F (25 to 30 °C), a pH between 5.0 and 8.0, and water hardness between 5 and 12 dH.

In the aquarium

A seemingly harmless, very active, social fish, they are best kept in groups of 5 or more and due to their potential size a 100 gallon aquarium should be the minimum size used. They also associate themselves easily with Panda corydoras and school together in currents. These fish have bifurcated subocular (located under the eyes) spines, which are used as a defence mechanism. If a loach deploys its spines while caught in a net, untangling it is difficult and can cause severe injury. It is also a good idea when moving larger specimens to double or triple bag them or use a solid container. Some owners have been stabbed while trying to catch or touch these fish. When kept in groups smaller than 5, they may spend more time hiding under obstacles in the water. Tiger barb also will associate very well with clown loaches, and they may school together. the tiger barbs will act in the same way as the loaches if they shoal, and vise versa.

They are also found to make clicking noises when excited or eating. This sound comes from the grinding of their pharyngeal teeth. Sometimes they lie on their sides on the bottom of the tank or swim upside down and appear to be dead. This is a common event and the aquarist should be aware of this fact or unnecessary removal may occur.

If you have noticed that your clown loaches do not come out of hiding, there are some easy things to adjust so that your clown loaches will be more comfortable. A good tank setup for a clown loach should include ample shade, real plants, hiding places and other peaceful fishes. Make sure the environment is not too bright initially. Provide shade from tank lighting. The tank should not be next to a window unless ample shade is provided. Window tanks with ample sun will allow Chromobotia to warm themselves and do their dominant color dances with more splendor as they flash in and out of sunlight slicing through opeings in natural cover. An example tank will have a powerhead to create a current for them to swim against as well as cover to stay under while doing so - think clear water mountain brook with current rushing from cascades deep beteween boulders. In fact, Clowns show a strong preference for larger rocks taken directly from mountain streams too swift to allow algae growth. They will peck at these rocks often and always sleep under and on them.

Clown loaches are keen observers of other fish in the aquarium; they observe and react accordingly. If other fish are skittish and hide, clowns will observe this and do the same. Make sure that other fish in your community tank are docile and not prone to hide. Chromobatia will all sleep together under their favorite collection of stream rocks. When other fish absently enter that territory and dither too long, the clowns will occassionaly react with a swarm behavior at which time (unfortunately) the errant straggler will experience with lethal outcome the thorns that give the Clown its second name, Thorny Eyes. We find that all-orange fish are prone to mass kill-offs regardless of where they swim, and this may have something to do with Tiger botia’s domainace color displays. However, overly inquisitive Glass Tetra and small slow-moving catfish can also fall victim. If the killed fish are not removed, the Clown pack will move the kill a short distance from the lair and wait until the fish decays into a white blob when it is rapidly consumed. Sometimes they cannot wait and will open the gut cavity with their thorns and mouths and immediately eat the victims guts and vital organs, something scaleless algae eaters may be most prone too. We have tried Beat (also an agressive species) with Botia and it is clear that safety in numbers holds true: the Beta will quickly begin to fray and need to be removed. Chromobotia do not seem to attack same-size or larger fish or any fish that keep away from their chosen lair. Perhaps Borneo mountain people who know the fish better could describe Chromobotis predation more accurately.

Because clown loaches come from rivers and streams, they are accustomed to having other fishes and plants in their environment. Not having plants and/or other fishes can cause clown loaches to become stressed and to go into hiding. Especially on introduction to a new tank, it is imopirtant that lots of placid, active smaller fish are present. Until you know what fish company they like best, use many colors and varieties of inexpensive minnows. Another important thing to remember is that since they do come from a fast moving river environment, they need a tank with lots of clear, well filtered and fast moving water which can be achieved with proper filtration and the use of powerheads. Stream rocks should allow resting back eddies as well as shade and cover.

Two juvenile clown loaches with ich. Characteristically, for this stage of infestation, both are hiding in an ornament.

Before introducing clown loaches to your tank, make sure the fish you currently have are compatible because aggressive fish will stress your clown loaches and may need to be removed. Clown loaches are particularly susceptible to Ichthyophthirius (ich), so they must be watched closely when initially introducing them to a tank and when new fish are added. Ich usually deals the typical clown loach a poor prognosis since the standard treatment is especially toxic to the clown's "skin-type" and the dose must be halved and is therefore less effective.

A variety of food should be provided for clown loaches, and their behaviour should be observed during feeding. In a community tank other fish may take the food before it reaches the bottom, where the clown loaches feed. 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), plant matter, freeze-dried (tubifex worms, especially if it is fortified) and frozen brine shrimp (always thaw frozen food to aquarium temperature).

Clown loaches are also regarded as a natural way of controlling an infestation of small snails in the aquarium. This being said, a person considering them for this purpose must also consider their future needs with regard to a large aquarium. A person getting clowns to remove snails in a smaller tank might be better served with one of the many other botia species that are as effective at the task but remain much smaller. Despite that utilitarian purpose, clown loaches are usually kept for reasons of appearance and personality.

See also

• List of freshwater aquarium fish species