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Reverse Color Change?


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  • Regular Member

Anybody remember when I was yapping about Blacky Fishie turning orange a while ago? She had several scales on her left side that turned from velvet black to metallic orange, same with a couple scales on her right side.

The other day I checked on that and they're all velvet black again :huh:

It was not an injury. She had scales scraped off before, and in that case it shows the pinkish skin underneath. But this was definitely metallic orange scales, I even held her in my hand (under water) and checked it out back then.

Is that something common? I always only read about them losing their black and turning orange, yellow or purple checkered. But I haven't read about them re-gaining the black. Well I guess it is natural or it wouldn't have happened. But how and why does it do THAT?

Don't get me wrong, I don't mind if she stays black. It suits her so well :)

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No, not really. The only thing that changed in lighting is that for a week now in the morning they get some actual sun in the tank. Not a lot, only in a corner of the tank.

The tank is bare bottom on a metal stand though, so when the sun rises it shines underneath the tank and so still illuminates the tank for hours every morning, from the bottom, reflecting off the wall and carpet. I wonder if that brighter, natural light caused this as people say that black is more stable in ponds due to sunlight (or maybe I'm confusing this with something else).

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Ok so from what I've been researching so far, hard to find research without having to pay for the papers.

Goldfish are tetraploids. That means they have 4 sets of chromosones from each parents. In essence a goldfish gets 4 chromosonal pairs while we have a single chomosonal pair.

I assume there is only one demelanizing gene which means there are 8 variations on that gene. This explains why some goldfish fade faster than others. i.e. Some have a DM gene concentraion of 1/8 and fade slowly while others have a concentration of 4/8 and fade faster.

But as we see in fry they are not born with color but develop it over time which means there must be a melanizing gene with that information coded. Now that is more complex, the main colors are black, blue, white, red, yellow (orange). But we also find milder versions of these with brown, purple, bronze etc etc...

In conditions that are more similar to their natural habitat (aka ponds) goldfish' colors will deepen and be more pronounced that the tank environment we provide them. I can only guess that certain environmental and hormonal triggers were genetically set up to aid in melanization of a fish. That would cease the demelanizing process while those were in effect. Your fish seem to either be melanizing as a result of environmental or hormonal stimuli. I can only guess the amount of variations on the gene involved with the effect of hormones and environment have on melanizing and demelanizing genes.

Needless to say, goldfish genetics are ridiculously complicated.

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