Dogface grow large and will eventually eat your smaller fish. I have a valentini he rocks, I just can get large snails in my tank or he will eat them. He stays away from the tiny ones, their foot is just too small. here is a pick of him sleeping:
Pretty aggressive. He's never gone after another fish - would be kind of stupid to go after a lion thoug. If you're thinking of getting one, I'd stay with other tank mates that are just as large and aggressive.