Thanks for the reply. There's only one clarkii, not a pair, and he is pushing 8 years old so he's long past maturity. Damsel has been gentle so far. Hasn't gotten in a single scrap in the years I've had him, and even ignores the Dalmatian mollies that I just added. No intentions of adding another clarkia either. So the Midas may be the bully of the bunch then?
Actually the Clarkii is likely a female if that old. With no male, behavior should be moderate to mellow. The Midas will not be a terror, but will likely nip.