My tank is 29 gallons .How big is your tank? There's a few options but they would probs "take over" the tank fairly quickly...
I would recommend pearl weed if it's a low-tech tank. I have it in my 180L and grows, well, like a weed xD
Trim the tops and it grows really bushy - would probably serve its purpose for fry.
Chuck some pearl weed in there and it'll do the jobMy tank is 29 gallons .