Ok, so I have 3 albino channel cats in my 55gal. I have a castle with many ways in and out for them to play/hide in. 2 of them are on the small-ish size. At least theyre skinny. The 3rd one however is probably about 8in long, and kinda wide. This is the one who was playing inside their castle, and attempted for about 5min to exit the castle through the SMALLEST hole there is. He was damn near stuck.