Some would say yes some no..
I have one in my 75gal and am wanting to transfer to my 100gal..
I'd say 100gal and at least 5 foot long.. yellows, purples etc would be fine in a 75gal but these guys are skittish and a little psycho..
thanks omega.. i've had him for about 2 years..and he is believed to be about 7-8 years unsure..