Any of the herbicides made up of glyposate that are used for emergent plants will do the trick. Even Roundup found locally will not hurt your fish although it is not specifically for aquatic application and allegedly is bad for frogs. I have not found that to be the case on my ponds. The Great Blue Herons are more of a threat than the Round up to the frogs for me.

If pigs could fly bacon would be harder to come by and there would be a lot of damaged trees.