The reason behind the disdainful gaze of Aster was simple, anacondas have forward-looking eyes placed on top of their heads and nostrils in a similar position for a reason, they are adapted to hide their otherwise easy to spot large bodies underwater, with only their heads remaining at water surface level.
Now you might think that maybe there is not a deep enough spot in the vicinity of this wetland area for them, but no, that's not the case, even from distance the group could see spots where the water reached as high as their waists, so that wasn't the reason as to why those three anacondas were laying down at plain view.
They simply didn't think that someone would come to their race's territory looking for trouble, and even if that wasn't the case, they thought themselves to be strong enough to not fear anyone besides certain specific beings like the kings.
