The Electric Fish is a key item gained after feeding a normal fish an Electric Worm which was given to Max and Monica by Osmond. It actually resembles a glowing yellow Bon in the end, no matter what fish it was at first. It was fed to Shingala which ended up breaking its mind control device.
This article is too short to provide more than rudimentary information about the subject. You can help the Dark Cloud wiki by expanding it.