With a tomato, I'd recommend adding three new clowns. I'd add the smallest male tomato you can find and get two of something else that can hold it's own. Marroon, Clarkii or a pair that at least has a female that is larger than the female tomato that you currently have. I generally wouldn't add any other clowns to a tank that already has a Tomato in it but since that's what you want to do I'd add multiples. That way if she does decide to be the aggressive $#@!% that I'm sure she can be, there are at least two others to share the aggression. Or you could just add a small male tomato.
- Personal experience -
When I transferred my 210 from a temporary location into it's new position and added the contents of a 125 and a 30 breeder, I added a 1" leucokranos first, the 3&4" perculas next and the 5&6" polymnus pair last. My female polymnus jumped almost immediately (she had light shock issues) and the leukocranos took the male role with the newly transgendered female polymnus. I occasionally see some brief chases, but there have been no fin nips or other signs of aggression in the 6 months the system has been running.