definatley black cons but in a tank that size with all those fish not a good idea the cons will make the other fish reteat in to a corner of the tank in days of them entering the tank
What if i get rid of all other fish accept the pleco, then can i get a pair of conflicts. by the way, wht if i try to buy some black cons, and get two males or vice versa??
if you want to breed the cons get a male and female, but i think they may beat eachother up if they were both male. i thought that a 30 gal would be a better size for a pair of convicts, but im sure they would be OK in a 20 gal.
Also the Salvini cichlids are an extremely aggressive new world that grows to slightly larger than a convict [male] , though I wouldn't put a pair in a twenty gallon .