question about my demasoni

My Dems arrived on Friday in a Fed Ex Box. They seem to be doing well but I'm curious about the top fin. They always have it folded down instead of up (unless of course they are chasing someone or making a statement). Is this normal for Dems or should this fin be up? Is it just that they need more time to acclimate? They are swimming fine, no signs of illness, and most have pretty color. They eat like pigs too.

Thanks!