You're right, the coloring is too light for Rouen. Also, the shape doesn't look right to me for Rouen. I've had Rouens. This one is more elongated, but not as much as a runner. Rouen duckling bodies are sort of rounder and flatter, like a deflated football-shaped patty rather than a tube or...
Ended up with a free mystery duckling yesterday. Still has egg tooth. Also some kind of white fluffy down at the sides of his mouth? Apologies for the blurry pics but he just would not sit still.
Anyone good with ducklings out there want to hazard a guess at what breed?
ETA: The Right Photos...