In my 45G i have 6 guppies, 3 pearl gouramis and a bristle nose pleco with my pair of cockatoo cichlids which have spawned twice since ive had them, but with there eggs prone to getting fungus neither batch of eggs hatched.
They arent too bad when they are guarding the eggs but once they are guarding free swimming fry, they will terrorize all of your other fish.
I now also have a pair of rams in a 15G which are great fish to breed aslong as you have a definite pair and the right water conditions, but these also are aggresive around their free swimming fry.
I would advise getting a tank just for your cichlids to breed in
