Fish colors

[Ttw]

When fish are collected in the wild their colors are often extraordinary. After a few generations in the home aquarium these colors fade. Feeding diverse foods has not really helped, at least in my tanks. Does anyone have a successful way of maintaining the wild colors?

 

[MacZ]

What have you tried besides food?
How did you manage the generations? Any inbreeding? Any linebreeding?

When we still bred Rift Lake cichlids we would switch the males every generation so no related animals would breed with each other. Then again, we rarely went over F3 or F4 before we sold all specimens of a species including the breeders.

 

[rasmusW]

Great question…
I have thought of this myself.
Could it also have something to do with water chemistry? Maybe there is a higher degree of irons for like red colors or something similare?
So the crusteans and insects the fish live of would ofcause also obtain these varying degrees of minerals.

I guess it could also has to with fish density. -in which “survival of the fittest” principels would fit. Making the males more vibrantly colored in order to scare off competitors and win in the females.

These things would ofcause take some generations.

I’m absolutely just guessing…

I thought of something similare when i saw Toms pictures of cacs and aggies from Rio corrientes. They both have much red in them (as far as i recall).

Looking forward to hear what others have to say here.

-r

 

[MacZ]

Maybe there is a higher degree of irons for like red colors or something similare?

Good point, as many natural bodies of blackwater have interestingly high iron concentrations.

 

[rasmusW]

ye!
i recently saw a documentary on either "cave paintings" or "medieval color dyeing" (-nice remembering, brain...)
anywho.. one of the iron rich clays they used was called something like cenepe.. (-again, nice remembering, brain...)
-i googled it but can't find the exact name.
this though, led me to think of the newly discovered nannostromus "super red"/cenepa.
i guess the name mainly refer to the catch location, but this area could also be rich in this type of clays.
the also newly discovered hyphessobrycon sp. amaya, is also very red and as far as i can deduct from a map it's collected in the same region.. -i could be wrong, though.

-r

 

[MacZ]

i recently saw a documentary on either "cave paintings" or "medieval color dyeing" (-nice remembering, brain...)
anywho.. one of the iron rich clays they used was called something like cenepe.. (-again, nice remembering, brain...)
-i googled it but can't find the exact name.

Good I studied medieval history.
Carmine, colkothar, kermes or cinnabar? Those are the ones you find in medieval manuscripts. Or iron gall ink.
Cave paintings used red ochre.

 

[rasmusW]

yeah! hmm.. not sure which of them it is. sorry.
it just resembled cenepe/cenepa.

-r

 

[MacZ]

Cinnabar, then, if you go by phonetic rules.
In the end all of them are iron-oxide or iron-sulfite compounds from different sources (minerals, earths, lice, snails)
Cinnabar is a mineral.

 

[Mazan]

The Cenepa is a river between Ecuador and Peru (there was a territorial conflict there in 1995). I don't think the word has any other meaning. Laterite is an iron-rich clay found in the Amazon and other tropical regions, it is usually quite red in colour.

 

[MacZ]

I don't think the word has any other meaning.

I agree, and if there is any meaning I presume it's from an indigenous language and as such not connected with the names for red pigments, as those mostly come from indo-european or asian languages.

 

[rasmusW]

The Cenepa is a river between Ecuador and Peru (there was a territorial conflict there in 1995). I don't think the word has any other meaning. Laterite is an iron-rich clay found in the Amazon and other tropical regions, it is usually quite red in colour.

yeah! i read that too. that's why i said, i think the main reason for the naming is due to the catch location.
but i guess this laterite, could have something to do with it then... -atleast it could support my theory.. hehehe

-r

 

[Ttw]

I manage generations by trying to pick the best looking parents as breeders. Since almost all the fish I have were collected by me there are not a lot of fish to enrich the gene pool. But this does not seem to be genetic since the color changes occur fairly quickly. I think it is environmental and diet. From observations of my fish the change is greatest in predominantly blue fish. These often came from water with lots of blue-green algae. Feeding spirolina has not improved the color. No evidence for any of this. Just my thoughts.

 

[MacZ]

Since almost all the fish I have were collected by me there are not a lot of fish to enrich the gene pool. But this does not seem to be genetic since the color changes occur fairly quickly.

How quickly? You write "a few generations" above.

From observations of my fish the change is greatest in predominantly blue fish. These often came from water with lots of blue-green algae. Feeding spirolina has not improved the color. No evidence for any of this.

That's interesting. Most blue colouration comes in the form of iridescence, so the scales have surface structures that reflect light blue-greenish. Actual blue pigment is extremely rare in animals. So question is: Pigment or iridescence?

If it's iridescence the lights and tint of the water might also factor in as influences on genetic expression.

 

[Mazan]

Interesting, the blue iridescence does not seem to be lost with many generations of captive breeding eg in electric blue acaras, rams, jack Dempseys....

 

[Mazan]

Well I tried to look up to see if iridescent colouration can be affected by diet or other environmental factors, so far did not find anything definitive in fishes (but need to look more carefully) but did find this:

Dietary protein level affects iridescent coloration in Anna's hummingbirds, Calypte Anna.​

Could it also be a sexual selection thing - in the wild there is more competition for mates so they have to be more colourful, I am not sure how many generations it would take to lose this in captivity where competition for mates is not such an issue?

Also: "Blue is an unusual colour in fish in that it is a result of black pigment deep in the skin, with irridocytes in the middle layers of the skin. The irridocytes interfere with the light to give a blue colour."

So the black pigment could be affected as well or instead of the structural part?

 

[Mazan]

Also in this paper:

Condition-dependent expression of pre- and postcopulatory sexual traits in guppies​

"Surprisingly, we also found that the total area of iridescent coloration was significantly larger in food-deprived males than their well-fed counterparts. One possible explanation for this latter finding is that a reduction in the area of orange coloration makes the surrounding iridescence patches appear larger and more prominent".

 

[Ttw]

Not all the fish lose their color over the same time period. In some it has taken several generations while others lose colors significantly in F1.
Interesting information on color vs iridescence.