Can one species of fish cross with another?

Probably not in the wild, but since some species have spawning periods that overlap, it is possible ? but only between very similar species such as bluegill and green sunfish.  In hatchery situations in Kansas, hybrid crosses have been made between bluegill and green sunfish (hybrid sunfish), striped bass and white bass (wipers), walleye and sauger (saugeye), and other species.