Chocolate cichlids. Drab when young and through young-adulthood, but they bloom into random, awesome colors when adults. Large, bulky, and very peaceful.
True Parrots, Green Terrors, Bocourti, Pearsei, and Vieja are all other large, colorful species that really shouldn't bother smaller tankmates.
That's assuming that I read wrong and you're not planning on housing whatever fish you get alone with a jaguar...