Many people house blood parrots with some of the more peaceful central and south american cichlids. Something like flag cichlids could work, angelfish, bottom feeders such as brochis (I wouldn't do corydoras they're a bit small) or smaller synodontis, or maybe smaller plecos like bristlenoses. Of course, you could devote the tank entirely to blood parrots and get a few more. Just make sure you don't buy the horrible injected ones, "jellybeans" or whatever silly name is coined on them.