Why are saltwater fish more colorful than freshwater fish?

Question

Oceanic creatures have all sorts of colors and elegant designs. Freshwater fish typically have bland colors and don't look as nice, why?

Answer 1

Ask God :)

Answer 2

Being a freshwater fish biologist I would not totally agree with that assumption. Many species of freshwater fish do indeed have much color. Like the bettas used in freshwater aquariums. There are several darters native to North America that a very colorful. I would guess you have never seen a orange spotted sunfish. And I totally object to the "don't look nice" comment.

http://campus.murraystate.edu/academic/faculty/howard.whiteman/field/fish/orangespottedsunfish.html

However, there are indeed more species of colorful marine species, fact is there are more marine species of fish that there are freshwater. There are several important reasons color is more obvious in marine fishes. Water clarity and competition are two. Not just competition for mates but also for territory or breeding sites. Also, marine fishes have been around many more millions of years than freshwater species.

You are correct about the "elegant designs". There is indeed more variety of body parts and fins in marine fishes. Here again there are just so many more marine fish species than freshwater.

Answer 3

Maybe it's because bodies of saltwater tend to be clearer and fish there tend to stand out to draw the attention of potential mates... while bodies of freshwater tend to be murky and muddy, and fish in those waters develop colors that help with camouflage? Just a thought...

Answer 4

Also, oceanic fish are usually silver and blue/green, not that much different in colour than a typical river or lake fish. I think you are referring to reef fish. If you want to see beautiful freshwater fishes you should check out the African rift lakes cichlids.

Answer 5

Evolution,marine animals communicate with colors,fresh water is often muddy or murky,negating color as communication.

Answer 6

Because saltwaterfish OWN freshwater fish

Answer 7

Salt is a cleasning agent.. may brush their teeth with it.
To occupy the water with salt in naturally inhibits a coloring with brightening the fish!
"Gramma says never borrow a cup of salt it brings bad luck!!"