Heres some answers to your question. Hope they help.
Hole in the Head
is a disease of tropical fish which starts with smalls sore on the head above the eyes. These sore grow and eventually penetrate through the outer layer of skin.
Hole in the Head ...
is the result of poor water quality over a long period of time. It's best to prevent Hole in the Head by doing the proper maintenance schedule
How to Treat Hole in the Head ...
you should immediately begin the recommended Maintenance Schedule and get the properly size aquarium filter with a BIO-Wheel. Then begin cleaning your gravel with a gravel washer. When the gravel is clean, remove most of it and remove the under gravel filter