Welcome Muck. If you can post a good, up close, pic of the weeds they will be a lot easier to identify.

That said, whipping any plant growth after it has become an infestation is almost a losing battle. As you kill it, the dying plants fertilize the ones that are still coming. I generally recommend that you start in the Spring when the plants are getting started.

There's a good chance that few if any fish are alive in it. However, it will certainly raise a bumper crop of mosquitos.

If it were me, and it's not, I would probably just put in some blue pond dye and have an attack plan for early Spring.

What part of Fort Worth?

It's not about the fish. It's about the pond. Take care of the pond and the fish will be fine. PB subscriber since before it was in color.

Without a sense of urgency, Nothing ever gets done.

Boy, if I say "sic em", you'd better look for something to bite. Sam Shelley Rancher and Farmer Muleshoe Texas 1892-1985 RIP