The first picture has some nice juvenile Jack dempsey (Roico octofasciatus), and the second is indeed a convict (Amantitlania nigrofasciatus). As mentioned above, you can sex the convict but whether or not there is orange coloration on its stomach. Convicts are very prolific if they are given a chance to pair off. In regaurds to their aggression towards other fish while mating, it depends on the tank size. I have had offspring in a 55gal-210gal with our too much trouble. A few nipped fins are bound to happen, but death of fellow tankmates is rare I.M.E. with a properly stocked tank.