I have 4 khaki campbells that are about 11weeks old. my concern is that one of them seems to be the runt. It is about 1 week behind the others in develpment, but it seems to have an adversion to water. While all the other ducks will get into the water and seem to love it but the runt does not willingly enter the water. It only gets wet when he alls in, as a result is fillthy, it's fethers are matted and looks very pitaful. It also behave strangely cooompared to the others it has not figured out how to go up the ramp to get into the house. Should I be concerned, and is there anything i can/should do?