The Clown loach is one of the most popular and loving tropical aquarium fish, but unfortunately its requirements are not often met.
For many, the word loach is widespreed with one particularly species – the Clown loach (Chromobotia macracanthus). These have long been the primary fish of community tanks and sold to newer aquarists to cure issues with snails.
However, the reality is a complicate fish with many requirements which must be met to ensure its wellbeing.
Most fishkeepers don’t realise just how big Clown loaches can get, as it’s an unfortunate fact that few have made it to adulthood, being both delicate and slow growing. To see a specimen of 25cm/10” or more is unknown.
Wild clowns are reported as reaching up to 40cm/15.5” and aquarium trophies are known to be up to 30cm/12”. On the downside, many larger aquarium examples have been poorly kept and are ill shaped and obese — far from an ideal that we aquarists would want to achieve.
Common ancestor Clown loaches are from rivers in Kalimantan and Sumatra, and made up of two separate populations. Based on genetic methods of ageing, it’s thought that the two shared a common ancestor around 9,000,000 years ago, but were split afterwards.
In that time, they have remained generally the same, except on a genetic level, and visually there’s little to tell them apart. Sumatran populations have red or orange pelvic fins, whereas Kalimantan types have varying degrees of black on theirs.
The environment in which they are found varies throughout the season, enabling the biotope fancier to choose between options. Even the water parameters where they are found vary over the course of the year, leaving scope for changing layouts over the course of the fishes’ lives.
For part of the year they endure a dry season when they prefer larger river channels where water movement is slower. This period may have water temperatures up to 30°C/86°F and be typified by soft substrates, acidic conditions and clear waters. A pH value of between 5 and 5.5 can be the norm and it’s easy to replicate such a tank.
Go for fine sands, leaf litter, rounded stones and some planting. Java ferns, in particular, look effective and can withstand the loaches’ grazing behaviour.
During the wet season, Clown loaches will move into faster flowing streams and tributaries. Here they prefer faster waters, higher pH values, and a lower temperature. The pH may rise to 6.5 or 7.0 with an associated increase in hardness. Water temperature can drop to 24°C/75°F. At the same time water may get cloudier with increased turbidity and oxygen levels.
Recreating this second environment should involve larger rounded stones.
Whichever the layout, Clown loaches love to hide and should be given bags of opportunity to do so. Tubes are relished and the fish will squeeze into spaces no wider than their own flanks — often numerous individuals cramming into one tight area.
This tube-dwelling behaviour is exploited to collect wild specimens, although trade in wild fish is now restricted — at least where larger ones are concerned. Populations have been affected by collection for the trade, historically speaking, and Clown loaches now in stores are often the result of large-scale farming or rearing efforts.
Complex hierarchy Depending on the time of year, Clown loaches can be found alongside a whole host of other sympatric species. Various Rasbora, such as R. dorsiocellata are not uncommon
Among their own kind, Clown loaches have complex systems of hierarchies, with an alpha — usually female — at the top and subordinates engaged in unusual interactions with each other.
One is that of shadowing, in which a small fish will press itself against a larger one and copy the larger fish’s movements. This behaviour isn’t always restricted to Clown loaches either, with young Clowns sometimes recorded as tagging on to other aquarium residents, such as catfish. This can become more obvious in situations where Clowns are kept in too small a shoal size.
Clowns are too often offered for sale in trios, implying that this number will be enough. However, these social fish should be kept in groups of at least five, though more are preferable.
Tank mates, and even the behaviour of the alpha, will have a huge effect on Clown temperament. Naturally unpredictable fish they will keep a close eye on other fish nearby, and appear to use them to gauge threat levels. If these dash for cover, the Clown loach will quickly do the same.
Bolder fish will tend to promote Clown loach boisterousness, although they will never be real ‘out and about’ aquarium inhabitants in the true sense.
Lounging layabouts Clown loaches have a habit of putting themselves into unusual positions and will often spend time lying on their sides, looking dead.
These odd ways of reclining are entirely normal for these fish and if you witness them you should neither try to intervene to correct posture, nor should you reach for the medicine cupboard. It’s just one of those odd things they do!
Snail eaters, but not destroyers Clown loaches are frequently sold ‘to control snail populations in a tank’ but this is mistaken belief.
Although they do eat snails in the wild, Clowns will not have an impact on flourishing outbreaks in your aquarium.
In addition, snail strike is often associated with excessive waste in the tank, which is something Clowns won’t tolerate. Their water conditions must be spot on, so the exercise of adding Clowns will often be doomed from inception.
Clown loach also relish ranges of insects, aquatic invertebrates, crustaceans and worms, as well as some plant matter. Many planted tanks have had the edges of leaves grazed by a peckish Chromobotia.
Offer a range of foods, with live and frozen featuring heavily.
Avoid flake foods that will lose nutrition by the time they are soaked enough to sink. Instead, think of pellets and granules — and a pellet that contains both shrimp meal and a plant source will suit these omnivores very well.
Health problems More so than many other species, Clown loaches are particularly susceptible to two kinds of illness.
The first is whitespot, and given that the fish has a layer of tiny scales — yet none on the head — it’s hardly surprising that they contract these skin-boring protozoans at the drop of a hat.
Combined with their naturally nervous character and likely high levels of stress created by transport and capture, it would come as no surprise if it was later revealed that their immune systems take more of a battering than many other fish.
Be vigilant for signs of whitespot, especially when first introducing them, and be prepared to treat in the event of early signs of outbreak.
Be careful over choice of treatment, as some brands claim to be hazardous to Clown loaches, although no literature details why this may be the case.
The second issue, childishly referred to as ‘skinny disease’, is most likely an internal, Spironucleus type of infestation. This is prevalent on newly imported fish, especially those that are then kept in high concentrations.
The illness manifests itself as a constant loss of weight, regardless of how much food the fish accepts. At points they may have a full belly, but of a knifeback appearance whereby muscle is wasting away.
Any Levamisole-based treatment will cure this, but retailers should always remedy the condition before selling on the fish. Never be inclined to buy any shop specimen that’s looking undernourished.
A thorny issue The name macracanthus crudely translates as ‘large thorn’ and refers to a spike the fish carries beneath each eye. In times of distress it is released from under a flap of skin and juts out sharply.
When handling Clowns, or when trying to net them, beware as these can easily pierce human flesh or become entangled. The larger the fish, the greater the hazard!
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