|MadSci Network: Zoology|
Lightning is a large discharge of electricity, but it is not always fatal to people. Some people have been struck by lightning more than once and survived. Water is a very good conductor of electricity, so when lightning hits a body of water, the charge is carried through the water to the ground. The further away from the lightning strike a fish is, the weaker the charge of electricity will be. Right where the lightning hits the water, it is probably strong enough to kill a fish. A little ways away, the fish might only be stunned. Further away still, it might feel the charge, but not be affected.
People have taken advantage of this, using electricity to stun fish for capture. This practice is illegal now, except where it is used only to count or mark fish for wildlife studies, not to catch and kill them.
As for why people avoid water, there's a very simple reason: since water is such a good conductor of electricity, it attracts lightning just as something metallic would.
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