hey, i have a dovii and it is in a 100 gallon for now, he is 4" now, he only hasa two tankmates, they are a 6" striped raphael, and a spotted raphael that is 4". he killed my grammodewho was a little bigger, and a salvin's cichlid, all thought hat isn't saying much because neither of those fish can really threaten him anyways. in about a year he will be near a foot long if not bigger, they grow very fast and arevery aggressive, he is still a little shy but he isn't afraid of me though. he is the coolest fish.