# Other Aquarium Forums > Freshwater Fauna > Characins >  Colour-changing tetras?

## CK Yeo

I bought these tetras all at the same time. All black.


One fine day, one of them decide to turn a bit reddish.


Didn't know tetras do that... now I am wondering if the rest will turn red also... anyone knows?

ck

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## Jungle-mania

What do you feed them with?

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## mickthefish

thats a female of the species CK.
mick

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## Jungle-mania

the female can change colour?

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## ranmasatome

no..the female is that colour

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## valice

Harlequins also have this red colour change... Are they also a characteristic of the female fishes?

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## mickthefish

i'm not sure if i understand you vincent, in the harlequins we get over here the brightest coloured are the males the females are usually a more golden colour plus they are a heavier looking fish, is that what you meant?.
mick

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## CK Yeo

Oh!, Thanks mick. That's something new and interesting. But I am quite sure it wasn't reddish when i bought it.

BTW, I'm feeding them Tetra bits. I don't think it is what I'm feeding them that's causing them to change colour.

On a side note, this female was flaring its fins particularly more than the males. So, tetras flare regardless of gender? 

ck

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## mickthefish

the food you give should make no difference in their colour, as to it flaring ive seen it but not very often maybe it's a bit confused, hehe.
mick

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## valice

> i'm not sure if i understand you vincent, in the harlequins we get over here the brightest coloured are the males the females are usually a more golden colour plus they are a heavier looking fish, is that what you meant?.
> mick


Ooops... Here the problem of rumbling into colloquial English... Actually, what I meant was that some of my Harlequins starts to develop this deep red colouration on their bodies... Does that mean that these guys are female too?

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## mickthefish

imo i'd say they would be males vincent, a picture speaks a thousand words if you have one.
mick

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## aquarius

It could be that they were fed food which contain some male hormons when they were in the farms but later after the hormones "wear out" they turn back to their original self.

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## stormhawk

CK, Tetrabits contain carotenoids I think, which will bring out more of the red pigment in the fish. There's nothing to worry actually. From what I see, your fish are still stunning.  :Smile:

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## CK Yeo

Hmm... this is an interesting theory. But why would they want to feed them male hormones to a fish that sells for only 30cents? I would think that the reddish would sell better than a black fish in this part of the world.




> It could be that they were fed food which contain some male hormons when they were in the farms but later after the hormones "wear out" they turn back to their original self.


Stormhawk, nice to see you "alive" in the forums again! Back to the tetrabit, it may contain come colour enhancing ingredients, but I don't think it is sufficient to turn a tetra from black to red. Or can it? But the rest of them are still as dark or darker than when I bought them.

BTW, the said tetra is still flaring like crazy and staking out a territory in my tank. Didn't know that tetras can be so interesting...

ck

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## ranmasatome

what?? dont think they can be so interesting??? what???? lol  :Grin:

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## zenscape

Perhaps their living condition in LFS might not be good before they turn to their "true colour" in your well fed and good conditioned tank. I bought a bunch of emperor tetras from a LFs and they all looked really dull. Barely after a week, I could differentiate the male from the female as the male bagan to change to beautiful colour and long finnage. I know they are coping well once they are drawing up their territory and flaring.  :Grin:

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## aquarius

> Hmm... this is an interesting theory. But why would they want to feed them male hormones to a fish that sells for only 30cents? I would think that the reddish would sell better than a black fish in this part of the world.


I have no idea why but from what i know when a male fish turn into female is usually because that fish have been fed with male hormones previously. From the picture the fish is definately a female.

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## budak

i think it's an established observation that female black phantom tetras will develop a reddish hue on their bodies/fins: http://freshaquarium.about.com/cs/ch...ackphantom.htm

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## raglan

> Hmm... this is an interesting theory. But why would they want to feed them male hormones to a fish that sells for only 30cents?


Tetra Colorbits were/are cheap food, like a fish flavoured cookie, and contain Red 3 erythrosine, the carcinogenic xenoestrogen or estrogen mimic. Estrogen pulsed at the right time determines if a fish turns male or not.

In the U.S., Erythrosine is banned for use in makeup, but it is still in food products...harder to remove from food ingredients (as it was long ago given permanent " OK " status.)

Not that this necessarily relates to the tetras changing colour, though it is a dye. Some kids get way way over the amount a normal adult gets per kg.(if they eat junk food)

Same goes for fish.

Certainly you can colour your fish with colour enhancers, even down into the stomach can turn red

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## CK Yeo

Yup. There is no doubt that colour enhancers are used in this hobby. It work wonders for discus and blood parrots. But these sell for more. And enhancing their colour improves their prices. 

But don't give farms to much credit. In this case, it is probably the natural maturation process for the phantom tetra. It is not value-adding to use hormones on a 30cents tetra to keep them male.

ck

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## raglan

Yeah, that makes sense. 
Some of them in these photos are quite red

http://fishbase.sinica.edu.tw/Photos...y.php?ID=10658

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