The Dark Lake area is really interesting, but I feel that it lacks a bit of moving life.
In the pools of what some players used to call the "Swamp of Sebek", there could be little creepers that wouldn't come to harm but actually would mostly run from people.
Into the deeper pools, could have those fish animations that now and then we get.
And, mudcrabs: the NWN aranea spiders diminished with barkskin or painted red (mudcrabs usually are red) would make awesome mudcrabs.