hole in the head

Question
i have a large chilid that is developing deep clean holes in its head any ideas  

Answer
Hi Mick,
It sounds like hole in the head to me. There are many opinions on the cause and treatment of this.  I have a large oscar that has the same problem and has had it for at least a year.  I researched every website and asked at every fish store about how they would suggest treating him and they were all different. What I did was to use a medication called Hole in the Head. I used as directed.  I did alot of water changes and I still do to be sure his water is as clean as possible.  I over filter his aquarium with a filter that is double the size for his aquarium.  After a year later he still has some pits in his head but is eating better. Is your fish eating? Sometimes they will stop eating and their poop will sometimes become really pale and slimey.  That may mean that they need to be treated with other medications but if that hasn't happened yet then we won't worry about that.  
Some of the opinions as to why this happens are really confusing. Some are: water conditions are not good and the fish is in polluted water, poor filteration and too small tank size causing water conditions to become toxic, some large fish are more prone to hole in the head, and finally the theory that it is a vitamin deficiency that is caused by not feeding a varied diet.  So you see you will have to decide what you think is the real problem causing your fish to have developed this.  I know it is rather confusing expecially if you think you have been doing everything right for your fish and now he is sick.  I would try keeping the water conditions as close to perfect by frequent water changes and using the best water conditioner. You might want to buy a water test kit to make sure you water stays in the correct water parameters. Make sure the your fish is in a large enough tank for his size.
I have also read that many large fish live for many years with hole in the head .  As long as you try to do your best in treating it that might be what your fish will do.
Best of luck.
Hope this helps!
Karen