like the above people said a jd will leave alone some fish that dont look like him.. therefore a senegal bichir will work, my jd never bothered my senegal bichir, but beated the heck out of my green terror, which were the same size, also 2 baby jds wont work out one jd will be more of a good fighter. try adding bigger aggressive cichlids than him like a red devil, or a bigger texas so it will hold it self, but then the texas will pick on the JD
JDs are aggressive, super mean fish, hence the name "jack dempsey", they live up to their name, fishes that my jd had left alone(mine is an sob like urs) was plecos, bichirs, ghost knife fishes, gouramis, but most cichlids he attacked no matter what, they had to be bigger than him, but i had a 4" Severum wit a 3" jack dempsey the severum would beat the jd in lip locking as he was bigger, and the sev is a peaceful so didnt chase the loser JD all the time