You can get away with a FM for a while, but adult size is 6 inches give or take. They grow slowly so if you plan to upgrade within a year or two you probably can do it, but only if you upgrade as they get larger.
If not, stick with a con. I know you don't want a dwarf, but they would fit best, and some of them look amazing. A cockatoo or Ram cichlid would look great if you are up to the challenge.