 One possible example in fish is provided by the electrolocating Peters' elephantnose fish (mentioned above as having one of the largest brain-to-body weight ratios of all known vertebrates).One captive individual was observed carrying a small ball of aluminum foil (a good conductor of electricity) to the outflow tube of the aquarium filter, letting the current push the ball away before chasing after it and repeating the behaviour.Captive white-spotted cichlids have also been seen hitting a floating thermometer hundreds of times to make it wobble and bob.