I have five clown loaches and five golden zebra loaches. They all like to sleep on their sides, upside down, on their heads, they like to flash, and twitch, and do all kinds of things that people normally worry about...truth of the matter is they are just being little goofs. I would imagine that is what is going on here too. One thing to consider is loaches are shoaling fish, so if you have less than three you might want to look into getting more.