luddocks are not peaceful..maybe at first but when setteled in can be aggressive as well. IMO wrasse aggression has to do with the shapes of the head, /complex it comes from. By in large all wrasses are wusses, but some dont like eachother at all, and that is were the aggression comes in. for example many say pylie are very aggressive, but i think often times aggression is mistaken for "displaying". Now of course when a fish is descaleing another fish and you can see it, there is a problem, but when fish are courting it is a much different story. In the end research will set you free. Read read read read read and read some more. then you will be better informed as to what fish should be skipped, and what ones shouldnt. I wanted gridled wrasse so bad, until i got one. Great looking fish, just the tude is nothing short of vicious. I think it has something to do about the "blue" complex. seems like "blues" are related, and therefore fight for dominance.