I have not done a lot of spearfishing, but I have noticed that in marine preserves the fish are much more likely to hang out, and they are generally larger as well. In hunting areas the fish always seem to be just shy of legal, maybe because the legal size fish are either gone, or smart enough to stay away from divers.
In Anacapa, we had a Large SheepsHead hang out with us almost the entire dive. I had been watching it for a few minutes lurking maybe 5' away. After a bit, the fish became very friendly, and started getting very close.
My buddy, who had not noticed it suddenly did so once it came right up to his face!
He cocked his arm back thinking that it maybe aggressive, and I started laughing! I tapped him on the shoulder, and told him it was OK.
From that point on every time we spotted a Nudi, or anything we spent time looking at, the fish was RIGHT THERE, swimming in very close to see what we were looking at. It was too Funny!