The post title asks if it's okay to have this fish in a 46, yet you already have it. If you're looking for validation, you'll get some, but your tank isn't suited to this fish long term. This is a fish that will easily hit 6 inches, and like all other surgeon fish, they are active. Since you already have it, there's not much point in debating the pros/cons. Doubtful the fish will thrive or grow to it''s potential, being stunted due to lack of space.