I don't dispute that you know what they look like. I'm merely saying that there are plenty of more attractive monstrous fish out there. I know you're only 13, so the 'cheap' price is appealling, but in my mind, you're better off saving up a little more and getting something that's more enjoyable and less of a burden (although, that's completely down to personal taste).
Chinese perch don't get quite as big, as the below link will state (70cm max). I can't comment on the aggression levels though, as I've never kept one myself.
http://www.fishbase.org/Summary/speciesSummary.php?ID=28054&genusname=Siniperca&speciesname=chuatsi