I've never heard Miamis can be aggressive, but I have heard that about Okeetees. My Okeetee is just fine, however. I've actually heard Miamis are NOT aggressive and are more docile, so you might want to double-check where you saw that. I have two Miami babies, but it's too early to tell how they will act when older. They don't try to bite me now, for what that's worth.