He will be fine with tankmates until he decides he isnt. Then they will all get killed in a night. Probably when he is around the 6" mark. I got mine because the lfs sold him 3 times previously to people with 55-90g communities and 3 times he wiped out all other fish randomly and 3 times he was brought back to the store. I kept him mostly solo. Id keep a half dozen rosie minnows and he would tolerate them for months up to about 8 then kill them all in an hour randomly. Careful with butti they are killers