You've got it! When it starts getting warmer, you'll see lots of bluegill and bass hanging around in the shade under the trees along the banks. Walk around the Basin, cast along the walls. Throw some casts out toward the middle. Vary how long you let your fly sink and the speed of your retrieve. Also, it's typically best (for fishing and for casting - fewer people around) in the early morning.
You'll see Snakeheads and Gar surfacing near the Ohio St. bridge, but good luck catching them!
You can catch a ton of different species in there! Largemouth Bass, Smallmouth Bass, Bluegill, Catfish, Carp, Longenose Gar, Snakeheads, Striped Bass, Shad, Black Crappie, White Perch, Yellow Perch...
Good luck! And let us know how you do!
--Scott