Why fewer fish in reeftanks than in freshwater?

[cygnus]

Marine fish cost a bit more than fresh water fish ,and like a few others have stated, saltwater holds less oxygen, and water chemistry is a PIA to balance. Fresh water fish are more forgiving of errors in chemistry. I keep fish in my reef tank just for movement and an extra splash of color, But the primary life is the corals. There are those that keep all fish (FOWLR) and those tanks are quite impressive it is a personal preference, i have noticed when you say "reef" most people think of mostly corals. I find myself doing the same thing. If someone tells me they have a reef tank I expect to see more corals than fish. You rarely hear of "Fish Reef" it is always called a coral reef. My 2 cents.