I kept an AT with some very aggressive cichlids. (managuense, red devil, pike cichlid, lamp. tetracanthus). They only seemed to bother each other. The AT stayed out of there way and eventually got to about 12-13 inches. I always used some salt and choral to keep it on the brackish side. Also kept an ST with a Dempsey and tried some african cichlids which were eaten during the night. The ST was much larger than the 9 inch dempsey, so there were no problems. I would suggest the AT because they are relatively plentiful and hardy. Dont put it in with a fish that is so aggressive that it had to be put into solitary. A cichlid community tank would be best and the cichlids will usually target each other.