I raised my green severum with my ebjd. Yes my severums is now 6" my ebjd is 4" the severum keeps growing and the ebjd seems to have stop growing. The ebjd did not like my severum but thing have changed. Like with all cichlids there will be some nipping but nothing bad. A 55 gal could work as a grow out tank for a year IMO. Sk I say go for it.