First: *Sati* I don't think Lori meant that salt water itself makes the fish look brighter, I think she meant that fish have adapted differently to light conditions over billions of years because of different refraction/diffusion properties of salt water.
My opinion is that it may have to do with *pH* and dissolved metals. Just a hypothesis, and not one that's supported by all instances (e.g. Lake Victoria). I'm wondering if the ions present in saltier/higher pH water enable the fish to brighten their colors. Prime examples of this apart from the oceans are Lakes Malawi and Tanganyika. This may be an issue of difference in water/light properties or a biochemical difference.
And though I agree with Alli in principle, I've still gotta say that if you walk into a fish store with FW
on one side and SW
on the other, you've got a huge difference in brilliance of coloration. Though fish like killies, cardinal tetras, bettas, clown loaches are colorful, I believe FW
fish are a little less vibrant. Are they less cool as a result? Certainly not!!! I'm much more interested by the morphology, breeding habits, behavior of FW
inferiority complex here--I'm very happy with my fish!