A few times (including currently), and they normally get along well but you need to tell us tank size/ size of specimens, other tankmates etc to form a better reply.
Currently i have a 4.5 inch Firemouth with a 4" male con, in a 130G with a few larger cichlids and silver dollars etc, they flare up every now and then but nothing unusual for central american cichlids. I've had other specimens swim alongside each other like they're best buddies in the past, and in smaller tanks.
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