I know you mentioned that you knew little about Oscars, but how much does you friend know? As Oscars mature, sensory pits will become more pronounced on their head. I wonder if this "friend" has mistaken sensory pits for HITH.
Someone gave me some free fishes, 3 very large Oscars. I really dont know much about Oscars, just that I know they are not my type of fish. Well I decided to give them to my friend. When I gave it to him, he told me that the fishes have hole in the head disease. When I looked at the fishes, they just had some marks on their head and that is what I saw. I did not know since I never kept Oscars before. I did not know they were sick. Well our friendship is runied because he thought I was trying to give him sick fishes.
I know you mentioned that you knew little about Oscars, but how much does you friend know? As Oscars mature, sensory pits will become more pronounced on their head. I wonder if this "friend" has mistaken sensory pits for HITH.
Actually your friend should exercise the habit of quarantine a fish before introducing it into the main tank. That way you can observe for sickness and treat it. Be it a reputed LFS or a gift from a friend, No exceptions.