Actually, they designed mazes for each set of fish to go through, using tank dividers and their own theories. Jamie used bright orange plastic and made them associate that with food to encourage them to swim through the holes. At the end of the test (45 days, I think) his fish would go through the three holes in around 40 seconds. Adam's 2 surviving fish didn't do as well with his designed maze. Still, theory busted.
I don't remember the exact name of the store. It was something along the lines of Goldfish World or Goldfish Heaven...