I have 16 that just came in Friday. I find this batch more alert and busier than last years batch but I wouldn't say they're aggressive. Are they attacking each other? What are you have them in? Are they under red or white light? I find if they have enough room they calm down in a hour or so.
How old are they? What are they eating? Are they getting enough?
Ours only get 'fiesty' if the feeder (i.e. me) is late bringing the food. And then it's all chicks for themselves! What a race to the feeders and getting in "their" spot to get some feed. Yes, our bitty roos are chest-bumping, stink-eye giving, sunspot stealing, who's bigger little chicks....but the hens generally don't even care another one is in their space....perhaps you have more roos than hens? This behavior started about 2wks old and now at 6wks old is really in full force.