Do Loaches sleep?
Loaches are not generally aggressive towards other species, but may fight amongst themselves. Keeping a group of 5 or more will generally lower the potential for harm.
Some loaches exhibit the amusing trait of lolling, or resting, on leaves or other surfaces which give the appearance of sleeping. This can be worrying to new fishkeepers, who may mistake the loach for being unwell, but it is perfectly normal behaviour.