Do Hervore or Omnivore Plecos go for Duckweed, Water Lettuce or Hyacinth?

[celticfish]

hi all,
just wondering if the above kinds of pleco go for these veggies?
i'm asking cos the pond at home is infested with the above veggies.
the two ABN i put in aren't making any dents obviously.
and we we moved back from house renovations i haven't populated it with any kois.
so they are growing like weeds! :eek:

[Edmundo]

i dun think so maybe the taste of the roots is awful?