If you keep or have kept tropical fish then there is a strong chance you will have owned Clown Loach at some point. They are an extremely interesting and exciting fish as well as having bold colours and stand out in any aquarium. When kept in a group the Clown Loach tends to relax a bit more and will often be found “chilling”.
It is this chilling out that brings us on to this topic of finding a Clown Loach on its side or back. This is exactly what they are doing, in the same way that we lay down to have a sleep, Clown Loaches will often rest on their side or back. This is more common when they have settled in an aquarium and found their spot to rest in which will normally resemble some sort of cave. You will find they will quickly react and come out of their coma should anything disturb them.
Obviously if they do not react normally and are very placid then concern should be raised however there is a strong chance they are just resting and there’s nothing to worry about.