A question about dragon elements?

So I've been playing with the idea of a book from the point of view of dragons for years now. The dragons have many different elements, and generally each element lives in a habitat suited to it. So fire dragons live near volcanoes, water dragons live in lakes and oceans, etc. But there are two elements I'm having trouble placing in any one habitat: electricity and poison. Do you have any suggestions for habitats for those two elements? Any help would be appreciated! ;)