I've been fortunate enough to see a total of 169 waterfowl taxa (and 143 species) across captive and wild settings - largely due to the fact I reached Blackbrook Zoo, and the extremely large collection of waterfowl held there, before it finally closed down.
In terms of wild waterfowl in particular, I have seen a total of 57 taxa and 50 species..... which I don't think is too bad going, given the fact my birdwatching experience has been limited to western and central Europe!
I have to admit to mild surprise that you have never seen captive Lake Duck! I've seen all three of the latter species in captivity myself, but the Lake Duck isn't particularly uncommon as far as I know.
That is when you look to quickly on a spreadsheet, it is Andean Duck I have seen only in the wild and Lake Duck both in captivity and the wild
Are you still counting the captive Ferruginous Duck from Munich on your wild list