I would'nt. I've heard a horror story or two about ppl trying to cut corners like that. I think distilled water removes impurities but, fails to remove all the chloramines. Also that DI water would need to be
re-mineralized because the fish would'nt be able to osmoregulate w/o mineral properties.
I read an article about this a couple of years back. I'm sorry but, I just don't remember all the details.
Well, You learn something new everyday. I just wish I could remember where I read that article from. Oh well...I'm glad that I have an RO/DI filter so I don't have any question about the water I use.