Mostly what I hear is that ducks and fish live pretty well together as long as one species does not outnumber the other. As long as the pond water circulates through and doesn't dry up, the ducks should be great weed and larvae eaters....I don't forsee you having any problems, just always remember that too much of one species in an area that isn't large enough is never good....I think your numbers are okay though. That said, Runners are my absolute fav, I have 2...
This is Ivy...

And this is Willow and one of my chickens Daisy

This is Ivy...
And this is Willow and one of my chickens Daisy