The well water should be safe enough for fish if it is safe for drinking. However, I'll agree with Tink that you should do all the standard aquarium tests on the well water, including kH and gH, so you'll know if you need to add anything to the water or worry about pH crashes. Well water shouldn't be chlorinated at all, so you won't need to use a dechlorinator. There are also tests for iron and such, but I'm not sure if it will be necessary to use them.
I'm sure somebody more knowledgeable/experienced will come along and add their

, and even help with interpreting your test results.