i dont know what a hongi is, but generally oscars are just big and hungry, not really outright aggressive (of course there are exceptions but im talking generally) so they shouldnt be housed with super aggressive fish
Hongi is an island/region in lake Malawi - many fish share that tag. The common name for Labidochromis sp hongi is Red top Hongi however they don't get 7-8" more like a not so robust 4-6" and could easily be eaten by a full grown Oscar. I guess 1st step would be to ID the "hongi" and find out how big that fish actually gets before he winds up as supplimental food.