Fish only tank

as I was driving home from the swap I was thinking about my neighbor setting up a freshwater tank and was wondering what opinions are out there about what is the bare minimum required for a fish only saltwater tank. Could you use regular aquarium gravel? do you have to have live rock? please post ideas. thanks

I have live rock, you don't have to but it helps with some of the shyer more senstive fish, plus tangs and angels like to eat algea off it, I think my trigger would have been very unhappy with no hiding spots. But I have seen several fake coral only tanks, you have to take out the decorations and scrub them frequently if you want them to stay looking nice though. Also you would need a very oversized skimmer if you have no live rock/sand. You can use sand/bare bottom/crushed coral, not freshwater gravel, that's usually painted or glazed with crap. I use a thin layer of sand for looks but have a ton of live rock. Lighting obviously doesn't matter.

You could also keep the salinity low (1.015), this would keep a lot of parasites under control, and wont hurt the fish.