Electrofishing is available in Sleepless Hollow when you acquire the Electroreel. To Electrofish, you must equip the Classic Red Hammer, and stand facing a body of water. Press the Mystic Power button to cast out your line (X or Shift by default). It costs 10 Energy to cast. Holding it down longer sends the bobber further out. The bobber will then slowly reel in towards you. If it lights up and splashes, a fish is on the line and you must tap the fire button very quickly (Z or CTRL by default) to catch it.