To properly keep an Emperor cichlid (Boulengerochromis microleps)
your tank should be no less than 500 gallons, probably closer to 1000 gallons.
It normally takes them about 3 years to reach adult size, and their life span is usually only a little longer than those few years.
So if you have either of those size tanks, fine, if not not, maybe the fronts, (or is it) Neolamprologus tetracephalus should be considered adequate.