It is indeed Elodea which is also known as anacharis. Search up anacharis and you will get the plant I am talking about. I have that plant in my 29 gallon and it is growing great with almost no maintenance. A good plus is that it is an ammonia mop. It will suck up a good amount of that dissolved fish waste so you can worry less about your water params. :) It looks nice too. Teachers call it elodea actually. We used it in biology last year lol. I was like omg thats my live plant!
~Budgies and Bettas~