well first i need to know how many of each but in a 29 gal 2 pairs at most and in a 55 gal 3 pairs after they grow up and pair off the rest will be hiding all the time or hovering at the top but this is about max size and just my experience. some rainbows and firemouths are pretty tame. and i am not sure what red head you mean you could also try cutteri or topaz ciclids similar to sajica
Is the Redhead a Synspilum? Is so, that will grow huge and dwarf all the others. The sajicas, rainbows, and firemouths go well together--in something like a 55 gallon tank.