I have a lutino oscar about 11inches right now, i call her grumpy, the other day she was upsidedown when i came home. i thought i saw her stop moving right in front of me and start to float up to the surface.. this fish then blurped out a huge peice of the polished river rock i use as substrate. and i could see two more stones down in its mouth..this poor thing was choking to death right in front of me. i tried to manipulate the fish with my hands underwater, but it wouldnt let me grip it will enought to open its mouth...miraculously it got all the stones out...so today i'll removing the stones and replacing with something smaller.