*** owned green terrors for years. If you get a male, they will somewhat get along with anything that isn't shaped like them. Plecos, loaches, catfish, sharks, I even had pacu as tank mates. They may nip from time to time, but no fighting. Docile tankmates such as these will steer clear and go about their business. If you stay away from simalar cichlid shapes (acara's, oscars, jd's, and mature rainbows) Males will hit them much harder. Females tend to get along better in community tanks, though they are not as flattering to look at. Kind of a toss up with a jd though. They, imo get along great with other cichlids *However!* I have a mated pair now and i think i have one of the meanest female terrors ever! Both male and female get extra snippy when breeding (a lot of people say they will kill everything in the tank, but i have never experienced more than some damaged fins and wary tankmates, though i dont keep other cichlids in their tank) She just cant seem to turn the bi*ch off. A first for me. However personalities will vary in these fish. I have had a few very docile and lovable females. If your looking to add a tank mate green terror, a female would be the safest bet with the fish you have. I hear that red terrors are about the same, if not worse with tankmates, though i have never owned any myself.