After things settle down, evaluate where you are. Toss in some fish food and see what responds. Odds are, you were gifted some fish from the river system, and gifted some fish to it. Bluegills, minnows, catfish...and carp will come to the fish food. It may take a few days, but that's a good way to start. If you aren't comfortable with what you are (or aren't) seeing, ask for more help.
Dave is likely correct, but I'd evaluate and then make a call.


Teach a man to grow fish...
He can teach to catch fish...