What size is the original? "Small" is a little veige.
Generally speaking you want to be sure the new additions is about ¬Ĺ the size of the original if possible. This will reduce any chance of the incumbant protraying the new arrival as a hostile and increase the chances of pair bonding. If the original is still only about 1" or so, it's possible it is still male or nueter.
As long as the new clown is either A. percula or A. ocellaris, the color is not important.