Well now....let's see..............
Largest cichlid.....There are several species of peacock bass (yes these are classed as cichlids) that get very large and I do know some who keep them in home aquaria!!
Largest Tanganyikan cichlid...Boulengerochromis microlepis....3ft plus!!!
I will do a search for the largest C/S American species when time permits, but I believe it would be.....Caquetaia umbriferus
CM