I agree with the others, unless you can do a 6 ft tank, best to stick to the smaller species.
Most cichlids go thru territorial phases that only become apparent after some time, when chaos breaks out.
Most available info does not get into this, and is almost impossible to predict in multi species tanks.
Nimochromis, all get too big for a 55, but even certain smallish species may find a 55 cramped.

I had a great long lasting colony of de-masoni in a 55 , but they were the only species in the tank, others (even larger species) were easily vanquished by the colony
.
I post photos , to show personal experience, nothing else.
And fish looks can be deceiving, the lepidiolamprologus below was quite benign with others, unless the other fish fit in its jaws

Most cichlids go thru territorial phases that only become apparent after some time, when chaos breaks out.
Most available info does not get into this, and is almost impossible to predict in multi species tanks.
Nimochromis, all get too big for a 55, but even certain smallish species may find a 55 cramped.

I had a great long lasting colony of de-masoni in a 55 , but they were the only species in the tank, others (even larger species) were easily vanquished by the colony
.

I post photos , to show personal experience, nothing else.
And fish looks can be deceiving, the lepidiolamprologus below was quite benign with others, unless the other fish fit in its jaws
