I wondered this also because you say your water quality is average. Maybe he will do that much better if you can get his water above average. I know keeping a solo oscar is hard because they are messy eaters. Maybe that extra food coming out the gills has his water not as healthy as you think. Now that you have the bp in there, it can eat the left overs and help keep your water quality better. IME oscars are always active in healthy waters unless they are stressed from other fish, bad water, or they just ate and they are stuffed. Lol