Can guppies change sex?

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Nabbig2

Fire Eel
MFK Member
May 28, 2007
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I have kept many guppies, and it seems that sometimes they change sex. For instance, I have 3 feeder guppies, and all were female, it seemed. I am sure, there was no gonopodium. This past week though, one of them grew a gonopodium, and I'm hoping it will mate, and produce baby guppies I can feed to my smaller fish. The male also has a black spot on it's tail, which I assume is only color, but it's not so colorful like other male guppies. So, can guppies change sex if needed? And these are feeders, not fancy ones.
 
Sorry, I simply had to move this thread out of "Other Monsterfish" ...

That "female" must have been an unrecognized male. A late developer...

HarleyK
 
No way can gups change sex. Marine Clownfish can, not guppies. You gotta start checking better. Take them out of the tank and ID them under strong light if need be.
 
Most of the livebearers can change sex if required. Swordtails, platties, mollies, guppies. Females changing to males although I havent seen males change to females. A fertilised female can retain milt for a few generations too so you dont necessarily need males in your tank to have babies.

I have seen fish farmers in Singapore sex sort fancy guppies at less than 1cm size TL (about 10 days old) with a wooden table, a trickle of water and 2 holes in opposite corners - male and female. They use the sun relection off body somehow. Amazing accuracy since it only takes one male amoungst females to ruin a generation of line breeding. The workers do this for hours all day everyday!!
 
fishdance;1016755; said:
Most of the livebearers can change sex if required. Swordtails, platties, mollies, guppies. Females changing to males although I havent seen males change to females. A fertilised female can retain milt for a few generations too so you dont necessarily need males in your tank to have babies.

I have seen fish farmers in Singapore sex sort fancy guppies at less than 1cm size TL (about 10 days old) with a wooden table, a trickle of water and 2 holes in opposite corners - male and female. They use the sun relection off body somehow. Amazing accuracy since it only takes one male amoungst females to ruin a generation of line breeding. The workers do this for hours all day everyday!!

You contradict yourself. How can sex-sorting be accurate if they can allegedly change their sex? No way.
Point remains: Females that turn male never were true females. They were unrecognized males.
 
HarleyK;1018173; said:
You contradict yourself. How can sex-sorting be accurate if they can allegedly change their sex? No way.
Point remains: Females that turn male never were true females. They were unrecognized males.

Sex change is not an instantaneous thing and may take a few generations of same sex populations to trigger. It is not clearly understood but it has been observed for a long time. I respectfully submit a link to a 1937 publication. (see partway down the first page)

from: www.goodeids.com/docs/Genetics_Platypoecilus_GORDON_1937.pdf

<quote>
WINGE (1923, 1927) has shown in the West Indian guppy, Lebistes, that
the X and Y occasionally cross over. In 1930 he stated that the genotypic
chromosomal constitution of XX for femaleness in this fish may be overruled
by other sex-determining factors so that the XX complex may occasionally
produce a male. These XX males when mated to normal XX females produce, as might be expected, IOO percent daughters.
</unquote>

Furthermore in his book - Livebearers: Understanding Guppies, Mollies, Swordtails, and Others; David Alderton writes - "[Females] can even undergo an apparent switch in gender at this stage as well, as the result of hormonal changes in their bodies following declining ovarian function. This phenomenon is most common in swordtails, but has been recorded in other common livebearers as well."

I suggest you try a google and make up your own mind since there is controversy on this but I personally have had swordtails and mollies "apparently" change sex and successfully mate other females to produce fry. Whether this is a REAL sex change or not I am uncertain.
 
It could be done after hearing what fishdance said, and it appears to make great sense. Although I too have had guppies and swordtails which I thought were males with a very short gonopodium but later turned out to be females after 3-4 months of age. But I am going to say that livebearers cannot 100% change sex. IE having the male genatiela, sex organs, sperm etc.
 
fishdance;1019675; said:
Sex change is not an instantaneous thing and may take a few generations of same sex populations to trigger. It is not clearly understood but it has been observed for a long time. I respectfully submit a link to a 1937 publication. (see partway down the first page)

from: www.goodeids.com/docs/Genetics_Platypoecilus_GORDON_1937.pdf

<quote>
WINGE (1923, 1927) has shown in the West Indian guppy, Lebistes, that
the X and Y occasionally cross over. In 1930 he stated that the genotypic
chromosomal constitution of XX for femaleness in this fish may be overruled
by other sex-determining factors so that the XX complex may occasionally
produce a male. These XX males when mated to normal XX females produce, as might be expected, IOO percent daughters.
</unquote>

Furthermore in his book - Livebearers: Understanding Guppies, Mollies, Swordtails, and Others; David Alderton writes - "[Females] can even undergo an apparent switch in gender at this stage as well, as the result of hormonal changes in their bodies following declining ovarian function. This phenomenon is most common in swordtails, but has been recorded in other common livebearers as well."

I suggest you try a google and make up your own mind since there is controversy on this but I personally have had swordtails and mollies "apparently" change sex and successfully mate other females to produce fry. Whether this is a REAL sex change or not I am uncertain.

lol how can there be generations of same sex populations? What does the first generation of same sex reproduce with if it takes multiple generations for sex changing to begin? :screwy:
 
Do a google and decide for yourself. I have already said that females can store sperm for several generations so you dont need a male each generation to have babies. This sex change has been recorded scientifically as well as anecdotally many times. In the publication I cited earlier, it states that XX females (males?) can physically change and mate with other XX females to produce 100% XX females. This XX factor is usually designated to females and was scientifically proven since this was a genetic study for sex linked characteristics. ie not a late blooom male of XY.

Protandrous fish as another example are nothing new. (Sequential hermaphrodite in which the fish functions first as a male and then changes to a female). Most people know the Barramundi do this for genetic diversity - so they dont spawn with thier own generation. Sex change in other species has also been recorded and accepted. Ornamental fish industry are very interested in sex control and reversal of many fish species for market reasons.

Does it really matter what sex the fish are if they can have babies? I am not asking you to believe in something you dont want to, I am expecting you to take a little time and reseach before deciding for yourself.
 
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