Sexing by behavior at 4 days old?

[Kansaseq]

Is it possible? My very first chick that hatched has turned out to be the most aggressive by far of all of the babies. Could it still be a hen? And if he's aggressive now, will he get worse as he gets older?
I do want to keep one roo, but not a mean one.......

 

[gritsar]

Nope behavior means nothing at that age.
My fiesty bossiest chick turned out to be my fiesty bossiest HEN.