That's a mess and has happened in a hurry. More than likely, some seeds blew in from another pond and got the cattails started.

Go to the Aquaplant website posted by TAMU. You'll find the right chemicals to take care of both problems. I get my chemicals from Tractor Supply Company but they seldom keep surfactants.

If the cattails develop a rhizome at the top, that's the seed head. Cut it off before it has a chance to mature.

I'll let someone else comment on aeration.

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