Hole-In-The-Head Disease (Hith) Is A Common Disease In Both Freshwater And Saltwater Fishes
the entire body of a fish.

It can be mainly an aesthetic problem, but it can cause secondary infections of bacteria and parasites. Minimize stress by keeping suitable species together and making sure your tank is big enough. If any of your fish show clinical signs, they should be moved to a quarantine tank.
. . .