Hole in the head disease or freshwater head and lateral line erosion (FHLLE) is a common disease that can be both treatable or fatal and it effects freshwater fish, such as oscars, cichlids and discus. The primary cause of FHLLE has not been determined, but factors may include parasites, stress or vitamin and mineral deficiencies.
Because many factors may contribute to the disease, treatment includes dealing with parasites, improving water and living conditions and supplementing nutrition. Antibiotics can be added to the tank and water conditions and quality must be thoroughly monitored. To prevent further infection, remove stressful conditions from the tank like overcrowding or water issues.