Alligator in convenience store?

A gas station/convenience store near my hometown in WI has a baby alligator in a 10 gallon gl tank, on display to the public. It's just a little guy, but whenever someone comes near it to grab an item to purchase it goes into hysterics; hissing angrily and trying to hide (there is no shelter for it, only a rock and 4 inches of water. Is it legal to keep it like this?? JW