Low hardness inhibits the flow of electricity through the water, and the body of a fish will be a selective path for current flow due to the higher specific conductance of muscle and normal bodily fluids. In very hard waters, the current will often 'flow around' the fish, since the water in this case provides the path of least resistance compared to the fishes body. Hence, lethal voltages must usually be higher in hard waters. Most outdoor ponds and tanks made out of metal or other conductive materials are prone to lightning strike. Even indoor facilities are susceptible.
Lightning can enter a building via utility lines, metal beams, water pipes or drains.
Most lightning rod experts are able to assess the likelihood of a strike in an enclosed building, and design simple protective devices to divert the electricity harmlessly to the ground. Clinical Signs of Electrocution Logically, electrocution occurs suddenly and the onset of clinical signs are equally acute. Mortality rates in any given group of fish hit by lightning can vary considerably. Usually most fish survive - although often with extensive injuries. Surviving fish often appear to have crooked backs and are unable to swim properly.