looks to me like Najas indica. The side branching is a dead giveaway~ The pic isn't great, so look it up and tell me if it is the same in person.
Najas indica is not guppy grass....Guppy grass is najas guadalupensis....I'd also vote for what I refer to as najas grass, or guppy grass. Coloration and like newby said the branching structure.
Are you sure?Najas indica is not guppy grass....Guppy grass is najas guadalupensis....
This pic looks like najas indica. Prettier, not as invasive...If the crown tops are thicker and more rigid, it is Najas guadalupensis or "guppy grass"
Check PlantGeek.net - Your Aquatic Plant Resource and look up Najas. You can differentiate from the two based on real life appearance. The pic isn't detailed enough so you have to take it from here.