There are blue runners too so that's a possibility for one of them as it goes look thinner in the photo than a typical blue swedish.
Edit: I just saw another photo here and it doesn't look more like a blue swedish than a blue runner.
From my research and talking to duck experts I've been advised that medicated feed is to be avoided with ducks in part because they do not need it and often eat more than chicks resulting in them getting a larger dose than the chicks :-) We cannot always get waterfowl crumble in our area so I...