Clown loaches are known for getting into the tightest places they can. They don't usually get stuck but I would keep an eye on him.
My husband(who was gone at the time) loves to tell the tale of how I hauled a huge piece of water logged driftwood out of a 75g tank, used a hammer and screw driver to chisel a clown I thought was stuck out of a tight fitting hole, then had to chase him all over the floor as he flopped around. The loach survived, hubby almost didn't

After a good friend finally quit laughing (he has a 21 yr old clown loach) he told me this was their habit and would probably have been fine.
Carol