It's a midevil.
Without proper documentation of its lineage, it's impossible to determine whether it's a red devil, midas, or other amphilophus hybrid.
As Wills mentioned, the fish isn't at 100% health. Good water and food will fix the condition, though you should note the white growth on the right side. I'd wager a guess that it's lymphocytosis, which is an incurable virus. Should clear up when stress levels reduce, as it's similar to herpes and is triggered by stress.