Saltwater and Freshwater fish

Aquariums have been a hobby of mine since I was 7…and I have always wondered: Why are saltwater fish, as a whole, brighter and more brilliantly colored than their freshwater cousins? Does salinity have any effect? For several species, it wouldn’t exactly fly as camoflage.

There is one particular family of freshwater fish known for its brilliant coloring (said to be the closest to saltwater)–African cichlids. These fish are found naturally in only three lakes in Africa, all three of which are very alkaline due to their rocky make-up. I’m curious if the alkali factors in at all. (Meanwhile, fish from acidic environments–South America/the Nile–are typically muddy looking.)

Any ideas?

I used to think the world was against me. Now I know better: Some of the smaller countries are neutral.

Laura’s Stuff and Things

Last I checked, most of the fish which live in salt water are kinda silvery with darker backs.

Now, the fish in the hobby are those that are more colourful. No one seems to want to spend thirty dollars on a herring, but you will shell out that much for a royal gramma or a Bursa trigger. Many of the smaller reef-dwellers are brightly coloured in order to advertise their presence (they can duck into the coral heads when danger comes near). Attracting the attention of other members of their species outweighs the need for camouflage from predators. These are the fish which are popular in the hobby.

Dr. Fidelius, Charlatan
Associate Curator Anomalous Paleontology, Miskatonic University
“You cannot reason a man out of a position he did not reach through reason.”

David Attenborough points out that the intense colors and patterns is to attract the female of the same species, which is extremely important in crowded reef environments. As proof, he said that in cases where a brightly colored species has been transported to a less crowded environment, the intense coloration begins to fade after several generations.

mips, that makes sense except the females are often the same coloration as the males. Is it then just a matter of species identification?

I used to think the world was against me. Now I know better: Some of the smaller countries are neutral.

Laura’s Stuff and Things

He wrote to attract the female but it probably must be a mutual attraction mechanism.

For several reef fishes, an adult male of the species is more brightly colored than a female or juvenille. This is especially true for parrotfishes and wrasses.

As a bonus, individuals in these (and other) species often undergo a complete change of sex, and therefore coloration, during their lifespan.

As mentioned in an earlier post, one reason saltwater fishes appear to be more brightly colored is because these are the ones that are most popular in the aquarium business. In actuality, a great majority of pelagic ocean fishes are silvery; benthic fishes are sand-colored, etc… Accordingly, many fishes that live on bright reefs are brightly-colored. If you think about it, a brightly-colored fish in front of a brighly-colored reef is afforded a considerable degree of camoflauge.

As for freshwater fish, they are probably less colorful for two reasons.[list=1]
[li]why waste being colorful in murky river water?[/li][li]where the river water is clear, it’s also shallow. Why help out the birds to find a quick meal?[/list=1][/li]

Judges 14:9 - So [Samson] scraped the honey into his hands and went on, eating as he went. When he came to his father and mother, he gave some to them and they ate it; but he did not tell them that he had scraped the honey out of the body of the lion.

The way I learned it, coloring serves three purposes:

  1. Attract the male/ female of the species
    (betas come to mind)

  2. Announce territory ownership
    (Garabaldis fit this bill)

  3. Announce that you are poisonous so others stay away
    (How about the Lionfish)

Attracting a mate has little or nothing to do with bright red and yellow coloring on marine fish - they’re camoflage.
In deep water, reds and other colors appear grey, because those wavelengths are absorbed by the water. Blue fish, on the other hand, still look fairly bright for a greater depth because the blue wavelengths are more energetic and able to pass into deeper water…


I just thought of something. Maybe freshwater fish don’t need to be as brightly-colored to attract mates because they mate at such specific times and places. Their spawning tends to be timed very specifically. I don’t know if this is true with coastal saltwater fish, who live in generally more crowded environments.

So in other words, where a saltwater fish says, “Hey good-looking. Meet me any old time. I’m the one with the sex green stripes on my flanks and the orange spot near my ventral fin” the freshwater fish says, “Hey good-looking. Meet me two to three days after the first glacier melt in a shallow eddy up the second river to the south of here.”

Fresh water fish have their colorful versions too. Trout, Salmon, Pumpkin Seeds (Pan fish better than a blue gill.), Guppies, Neon Tetras, Grommies, Bettas, and more.

I think it has more to do with what water visability is like where they normally live.

I’m only your wildest fear, from the corners of your darkest thoughts.

What, and that’s not the case with freshwater aquarium fish?

I would presume that for both branches of the hobby, the brightest colored (as well as smaller members) of the piscine families are selected due to their visual appeal. Of course, there are brightly colored FW fish–Bettas, goldfish, discus, African cichlids, pumpkinseeds (I used to breed them), neons/cardinals–but for the most part, they are a plainer lot, color-scheme wise. Even those which are colorful, such as neons, trout, and various sunfish types, are still dominantly silver. Regardless, these colorful FW fish cannot compare in intensity and sheer proportion of body coloring (the entire body being involved, rather than a stripe or pattern) to tangs, damsels, wrasse, parrotfish, saltwater angels, butterfly fish, triggerfish, etc.

Even comparing two solid-yellow breeds reveals a difference: the freshwater lemon labidochromis is about as yellow as they get, and it is lovely. But it is not as smooth, bright, or screamingly eye-catching as a yellow tang.

Sure, there are plainer colored SW fish. But my point and original question centers on the difference of intensity in the colors as much as the varying number of colorful breeds.

I’m beginning to agree that camoflage has to be part of it; my african butterfly (fw) is brown and mottled, to match fallen leaves that rest at the surface where he spends most of his life. There are no fallen brown, decomposing leaves at the surface in ocean life.

I used to think the world was against me. Now I know better: Some of the smaller countries are neutral.

Laura’s Stuff and Things