covered in  Yaéré  grassland of  Echinochloa  pyramidalis ,  Vetiveria nigritana ,  Oryza longistaminata , and  Hyparrhenia  rufa . [ edit ] Fauna There are many  floating islands  in the lake. It is home to a wide variety of wildlife, including  hippopotamus , crocodile  (both in decline here), and large communities of migrating