Twilight Princess: Barnes is a Poacher As Well As A Bomb Maker
Oh Barnes, you are possibly the most beloved character in Twilight Princess, right up there with the mailman. And who better than he to be a poacher? Just think for a few minutes. He only ever makes one real type of bomb, the basic one. The other two, the water bomb and the bombling, are found in the wild, doing their own thing. Now, if he were just an ordinary bomb maker, he wouldn't have any idea that the bomblings or bomb fish existed, so he couldn't have modeled it after them to be funny.
But I know what you're thinking. How could Barnes get into the Forest or Lakebed Temple? Well, at this point, you cleared the Forest Temple of dangers, and we can assume that bomb fish roam around Lake Hylia outside of the temple.