Can a loach get stuck?

[ewurm]

They also have things called subocular spines by thier eyes, which I imagine if stressed (thats usually when the spines come out), could aid in them getting stuck further.

Usually these are only deployed as defense, so I doubt that would contribute to the problem. The major problem that I can see is that a loach can easily swim into a crevice, but the pectoral fins would prevent it from backing out.