My Oscar has a growth on the side of its head?

[arthurf]

I have an Oscar that is about 5 years old and has recently developed a growth on the side of its head. It’s almost the opposite of hole in the head disease. 
The tank has been stable for years and i probably don’t do maintenance quite as much as I should… does anyone know what it is and what I can do about it?

[Colu]

You can get these types of lump with hold in the head am assuming your already treating with metronidazole in food for the hold in the head if not I would start treating with metroplex in food feeding a small amount twice a day for Upton 3 weeks hole in the head can be associated with  nutritional deficiencies poor water quality some state a link with active carbon so it your using active carbon I would stop  using it what are your feeding and what are your water parameters @arthurf