Do you mean like a non-cichlid dither schooling fish? Perhaps a school of congo tetras might work? I have never kept them with cichlids other than discus, & they're river tetras so I am not sur eof their water parameter requirements, but they're hardy & would get as nearly large as the attenuatus & they're very fast. They will also inhabit the mid-upper water column leaving the attenuatus to rule & reign the lower water column. Worth looking in to perhaps 
