From what I've read so far, the MAGICAL WATER (it's a powdered product) enables marine and fresh water fish to live in the same tank by just adding electrolytes to fresh water... You just dissolve this thing using tap water and you're set! :fish:
I was going to link to an older thread about this stuff, but I saw that Nymsley beat me to it. Check this out, and I'll let you form your own opinion (read Post #13). I said all I need to say about this stuff in the previous thread.