looks like a Lotus or Nymphaea to me. Does it shoot leaves that try to race to the water's surface? A better pic is needed but it definately is not an Anubias. I think it is Lotus or Caladium which is a tuber.
OK, hopefully this is good enough.
It is about 10" tall with a few 4"-length leaves. It is quite rigit when out of water, and a slow grower - only 1 small leaf after several weeks.
Sometimes the attached pic won't show - try right click on it and delect "Show Picture".
Thx for looking.
Ahhh now I can see it better. It is Syngonium podophyllum covered in algae....and it is not a true aquatic. It5 will rot. Because it is a terrestrial and slow to grow, it will only facilitate your algae issues and rot in your water. Pull it out and place it in a pot in moist soil and put it in a sunny window. Replace it with a fast growing stem and get a handle on the algae problem.