Sobered by store closings and the rise of online shopping, owners of U.S. shopping centers are filling space and drawing visitors by turning to unusual tenants like gun ranges and go-cart tracks.

Mall giant Simon Property Group Inc. opened an aquarium in July at its Grapevine Mills mall near Dallas. Real-estate brokerage Jones Lang LaSalle Inc. put a fencing academy in a former Old Navy store in Florida's Tallahassee Mall, and a community theater on the lower level of a former Boscov's store in Harrisburg, Pa.

Aqua...