River Piranha Plants appear to be a Piranha Plant's red and white head on a lillypad instead of its usual stem. Unlike the Piranha Plant, River Piranha Plants don't have any sharp teeth. River Piranha Plants are always seen blowing a green ball with yellow spikes.
River Piranha Plants are always found on top of waters, staying in place and blowing a harmful ball up and down. They can be easily be disposed of, as they can be killed by many things.
When hit by an iceball, they'll lose their spiky ball due to the fact that they can't blow it while frozen. This makes them panic, but they'll still stay in place without a ball until you leave the area and come back.