dude... i LOVE convicts and all and though of having a pair in m 125 buuut when i lived in the apts on my own i had a 20 long divided with 2 pairs and boy that didnt look so good either.. even tho the tank was divided they still went after eachother! they never stopped going after eachother and flaring through the glass. stressing themselfs out and me to trying to figure out what to do with 2 pairs of cons... so i wouldnt advise haveing a pair with any other cichlids unless you want a blood bath or the tank is divided.... try a pair of sevs and ONE male convict..... and no the fish dont grow to there tank size or there water quility ( sp ) they grow tell there stunted in a smaller tank ( there outside stops growing but the inside keeps going and killing the fish slowly ) so in the 55 have a pair of sevs and 1 male convict with some dithers to distract them from aggression..