The less aggressive and smaller clownfish are the Ocellaris Clownfish, Percula Clownfish, and Skunk Clownfish. Cinnamon's, Tomatoes and Maroon's are known to be the most aggressive clownfish. The remaining types are somewhere in between.

Well after 7 months peaceful since i introduced another pair of percula. My tomato clown was acting like a referee that prevent one pair from travel to another pair host. Yesterday, he took a day off and the warfare started and now all fours are fighting for one host. GREAT, now one pair has to find a new home.