Julie ornatus or transcriptus would work great. Both are small and very relaxed IMO. I keep J. marlieri, dickfeldi, regani, ornatus and transcriptus. You might even get by with dickfeldi too. They are very nice fish, maybe a bit more dangerous in a community tank due to them being a midsized Julie. It would depend upon tank size too. As long as they had territory to defend if they started breeding, there wouldn't be an issue. I have a breeding pair of J. ornatus in with a small calvus and there aren't too many issues. They don't like him, but they don't chase him all day long either!