To perform this trick, the skateboarder first gets a lot of air. While in the air, the skater reaches down his or her back arm behind his or her back leg, and grabs the middle of the skateboard between the feet (this is the heel edge of the skateboard).
When doing this grab, the skater also bends his or her knees and points them towards the nose of the skateboard. The Stalefish is a difficult trick, and requires the skater to be very flexible.
The Stalefish has jumped over to other board sports too, like wakeboarding and snowboarding. However, it was first invented in skateboarding, though no one can say for sure who made it up.
The most popular story is that Tony Hawk invented the trick at a skate camp in Sweden. He didn't have a name for it yet. That night, the dinner was some fish that didn't taste very good, and in Tony Hawk complaining about the meal, a skater misunderstood and thought he was naming the trick "Stale Fish".