For a Halloween carnival: what can I use for slime to fill a duck pond game? It needs to be slimy, but "flowy"

I'm putting together a Halloween themed carnival. I know it seems early, but everything needs to be organized by the middle of September. I am going to be running a duck pond game in which kids pick a rubber duck out of a wading pool full of water. I'm getting glow in the dark ducks plus a black light to make it more "spooky", however, I thought that it would be neat to have slime instead of water. I need a slime that is sticky, yet flows enough so that the ducks can move around-does anyone have any suggestions? Thanks a bunch in advance!