Aggressive cichlids usually kill all tank mates, and when the tank mates are gone, they hide.
And in a tank as small as a 75 gal, or even smaller, a 55, your choices get limited.
And if what you mean by aggressive is predatory, these cichlids are usually lurk and strike predotor, which means once they capture food they take it to a place to hide to digest it.
My Lepidiolamplrologus elongates was quite the killer, took him about a second, and then he'd loll around in one spot until time to eat again.
A 75 might be OK for him temporarily, or one of his smaller cousins like, Lepidiolamprologus kendali, but I must admit, he was not the life of the party