Most fish live in either freshwater or saltwater, but some live in both. In this Question of the Week we find out how these fish manage to avoid becoming too salty or too watery. Also, we ask if you burn your food, do the calories go up in smoke, and if a second lightning strike can act as a defibrillator, re-starting your heart after the first bolt stopped it?! Like this podcast? Please help us by supporting the Naked Scientists