Welcome to the PB forum, luvmypond!
It sounds like you're enjoying your pond and have already met your goals--swimming and enjoying fish/frogs.
When you say Sunnies, are you referring to Green Sunfish (GSF), Bluegill (BG), or another species?
Cattails can be very invasive, of course, but I've found that they're a nice hiding spot for the fish when contained to a delegated area.
"Only after sorrow's hand has bowed your head will life become truly real to you; then you will acquire the noble spirituality which intensifies the reality of life. I go to an all-powerful God. Beyond that I have no knowledge--no fear--only faith."