The darkest/blackest adults will come from a baby that has a black head..Many of the chrome/gray heads will also become very dark/black adults..Babies with cream/tan/brown heads are not as likely to be as dark/black..As far as reds go you'll want to see the parent stock for the best prediction.."IF" temperment is of any concern I would lean twords the black/curtus..I would also consider a borneo, but then I'm a borneo/brietaholic, LOL..Unlike the 2 you mentioned you can find 6 or more colors in a nice borneo..