Thats exactly why I ground my tanks. Not leathal (to most) but to be avoided. I also see it as a way to direct any rouge "waves" or "signals" out of the water into the ground. Most sealife have finetuned sensory organs that pickup on elctromagnetic and in some even incredibly weak electrical signals that detect THE SLIGHTEST current, even the firing or neurons that activate muscles! More prevelant in active preditors like sharks, especially eels, ans others with highly developed lateral lines. We did experiments with tesla coils and saltwater eels in my Marine bio labs last semester...the eels in the ungrounded tanks quickly found thier way onto the floors. Completley uncorrelated as of now (officially documentd and widley accepted) but my "predetors" and clams seem to be very sensitive to lots of appliances.