Clown loaches are agile, intelligent and very exciting fish that will bring a huge amount of action into your aquarium. Still, clown loaches are rather not recommended for fishkeeping beginners and that there are several aspects that need your attention.
Clown loaches grow slowly and they are - as soon as they have settled - very robust and can get very old (I have heard of clown loaches with 18 years of age!). The most problematic phase in keeping those animals comes directly after acquisition. A lot of times, clown loaches are caught in wild life (see also origin). Clown loaches will be weakened because of catch, transport etc. The next change - into the aquarium of the buyer - is another strain for the fish. During this period, clown loaches are prone to Ichthyophthiriose, but it can be treated using the right medication. In case of aquarium relocation similar advices can be applied.
It is quite normal that clown loaches won't show up during the first days and weeks in a new aquarium. Probably you only see them during feeding times. Little by little your clown loaches will gain confidence and will start showing their playful nature.
In order to minimize relocation or moving stress, the new "home" should be setup species-appropriate. Additionally, you should accustom an exact view for already existing diseases before buying a clown loach. If it is possible you might want to offer your new clown loaches a quarantine tank for a short period of time. Unfortunately this has the disadvantage that fish will have moving stress again as soon as they are set into the main tank. In any case you should grant rest to your animals during the first days.
Although clown loaches are very lively, they like to have caves and areas where they can withdraw and hide. Caves, tubes, stones and areas with dense vegetation is an absolute must have for a clown loaches tank.
You can imitate caves by using roots, stones, cocos shells, pipes and other elements alike. Tubes that are about double as long as a clown loach are best, their diameter should also not be too big.
The size of your fish tank is also an important point to consider. Clown loaches will stay in lower or medium water layers most of the time, therefore width of the aquarium is more important than height. In regard to length of the tank I have read about very different minimum values. However, according to my experience, tanks should have an absolute minimum of 150 cm length (375 litres), but all larger aquariums are better. In captivity, clown loaches still might reach 16 cm.
Clown loaches love to search for food on the ground, therefore sand or very fine gravel should be chosen as flooring. In any case, sharp-edged substrat should be avoided.
Because of their body shape, clown loaches are regarded as residents of fast flowing waters. Therefore, you should make sure to have at least a small stream in parts of your aquarium.