not really overstocked but inappropriately stocked. clown plecos grow pretty slowly. it's convenient to say "no it can't get the pleco, the pleco hides on a shelf" but is it really fair to force the other fish to hide all the time to avoid being eaten?
not only that, but if your clown pleco is a Panaque maccus (rather than a peckoltia pulcher), it *requires* driftwood as a part of its diet. panaques are wood eaters for the majority of their diet - it is what they are designed for. they can go a long time without it, but eventually they will waste and die. even if wood is introduced later on, it is possible that the cellulose-digesting bacteria in their gut have already died, and the plecos will starve to death with plenty of food in front of them. i recently went through this with some imported lyretail panaques - it was not a pretty sight, and there was nothing i could do.
not only that, but if your clown pleco is a Panaque maccus (rather than a peckoltia pulcher), it *requires* driftwood as a part of its diet. panaques are wood eaters for the majority of their diet - it is what they are designed for. they can go a long time without it, but eventually they will waste and die. even if wood is introduced later on, it is possible that the cellulose-digesting bacteria in their gut have already died, and the plecos will starve to death with plenty of food in front of them. i recently went through this with some imported lyretail panaques - it was not a pretty sight, and there was nothing i could do.