Why do my Oscars have gashes and many scratches. They don't fight too much.?

I have two Oscars, regular Tiger Oscar and an Albino Oscar, the regular one is about 6 inches whilst the albino one is about 4 inches. However, the black one has damage all over his body, from his skin having white scratches all over him and a huge deep gash under his swimming fin which was red/meaty color. The smaller one has little to no damage and both live happy in their tank. I have a 25 pound limestone in the tank and a coral. The tank is fairly large (90 gal), MY assumption is that he's running into the limestone/coral. When they fight they usually lock jaws or follow the other or even bite each others fins, but the Albino one seems more aggressive which he was never like that. The regular one would always pick on the smaller one and now it's opposite.