oscar fish. not sure what kind might be tiger

Question
my question is Angelo is trying to scratch himself his color does not look good. he is in a 38 gal alone. i think he likes that. he swims fine and i play with him when i am changing his water. but lately he has been going to the bottom of the tank and laing sideways and rubbing against the rocks also he stays upunder the filter, he seems to like water running on his back. he eats fine. I give him bits of bread not all the time and he eats these pellets that are to make his skin shine he has a hint of blue on his fins and he is black and white strip, but you really can't tell because he looks gray now. he did have some algy in his tank and on his rocks. it has been really hot in my apt me. no matter please help me. I love my Angelo. and advice or suggestion is all welcome. thank you in advance

Answer
How long is angelo?  How long haveyou had him?  Bread is not good for oscars, i would suggest frozen brine shrimp, blood worms, frozen beef heart and the cichlid staple pellets.  Oscars get very large, and need 55 gallons each.  I would suggest upping his space. Also how often do you change his water? With a messy fish like an oscar, you need to change 50% of the water each week.