Swordtail Sex Change

[Annastasia]

This seems to be a heavily debated topic everywhere. Some people say it's possible, some don't. I'm interested to hear your opinion. I know we are all nice, kind people here, so let's stay that way. No serious arguing, or criticizing people for their opinions, okay? Just keep it nice.


I'm personally skeptical. I can't say I've ever heard of, or seen a fully functioning female, that has given birth, become a fully functioning male that can impregnate females.

A few things that I read that might be of interest:

It is thought that one reason might be that the immature fish have the potential to be either sex. It is suggested in some fish that the ovaries grow more quickly than the testes to produce a female; in the remaining fishes the opposite occurs to produce males. As the females grow older, their ovaries cease producing hormones and the still undeveloped testes begin to produce hormones, causing the fish to devleop certain male characteristics.

Occasionally, true females suddenly begin to develop male characteristics, such as a gonopodium or sword, but these sex-reversed fish are almost always sterile.

Enviromental factors can influence the initial 'decision' as to whether an individual fish becomes a male or female. Low pH in the region of pH5-6 can cause more males to be produced, for example. Sex reversal has been seen in the wild with Gambusia Affinis, and in at least one case, it is believed to have been caused by pollution

All excerpts ©Peter W. Scott

Something to think about, huh? So what's your stand? If it's for them being able to change sex, can you prove it? Not just 'Well, this happened to me' but true, beyond reasonable doubt proof?

 

[guppymad]

i know its true, i had 6 swordtails (2 males 4 females) and 2 of the females changes to males.

 

[Annastasia]

What age were they? Had the 'females' had fry before? Were they able to impregnate females after that? Surely able to impregnant them? Not just that the females got pregnant, and it could have been from another male or stored sperm. Any information you can give would be great, as 99% of these cases are late-developing males.

 

[guppymad]

What age were they? Had the 'females' had fry before? Were they able to impregnate females after that? Surely able to impregnant them? Not just that the females got pregnant, and it could have been from another male or stored sperm. Any information you can give would be great, as 99% of these cases are late-developing males.

they were about 4 months when i got them and i had them for 5 months before they changed, they both had fry(well i had alot of batches of fry so i think they did). after they changed they were sterile.

 

[Annastasia]

Okay, so it's possible they were late-developing males. You're not sure if they had fry, and you're not sure if they could impregnate females afterwards. That's perfectly fine, I know how hard it is to keep track of Livebearers and their fry! Thanks for your response.

 

[guppymad]

Okay, so it's possible they were late-developing males. You're not sure if they had fry, and you're not sure if they could impregnate females afterwards. That's perfectly fine, I know how hard it is to keep track of Livebearers and their fry! Thanks for your response.

i think it wouild be great if some one did an experent to try and prove/disprove that it can happen or not

 

[dwarfgourami]

Agree with guppymad, it would be good to see this studied under controlled conditions. I have never experienced it myself; my swordtails stayed as they were. It doesn't seem impossbile, considering some of the weird things we now know take place in the animal kingdom, but again, very hard to be sure in most cases.

Presumably (or so I believe the argument goes) this change (if it is indeed a genuine sex change) happens when there is a severe shortage of males; otherwise Mother Nature would have no reason to arrange for this.

On the other hand, you would only know it had happened if a) the female in question had already given birth in the past, so was a bona fide female B) was then able to impregnate some guaranteed virgins (=no sperm stored from before).

Which makes the whole thing very difficult to arrange on purpose IMO. You would need to bring together some female who had already given birth (but was guaranteed not to be pregnant) with some who had no other option of obtaining sperm (but at the same time were not past fry-bearing). Or have I missed something?

 

[bleechme]

It think guppymad has a GREAT idea, but it will be time consuming since Live bearers are SOO easy to breed, we need to take a lot of time in finding unpregnant females (to test if the "mysterious females that turn to males" can pregnant a female) and there will have to be a lot of single tanks to test them in so you know how gave birth and ect....

 

[lilfishie]

my friend had a lone female for ages then it suddenly grew the sword but that was all no gonopodium

 

[bleechme]

my friend had a lone female for ages then it suddenly grew the sword but that was all no gonopodium

how long was "ages" I'm courious and want to know This subject interests me. If I ever go into a genetics major, I'll like to work with these fish for sure!

 

[lilfishie]

about 2 years

 

[charlie d]

Early last year I had a lot of baby swordtails in one of my tanks. I managed to off load them on to my lfs but didnt realise that I had left one of them behind.
I then moved the parent fish into my other tank, but before the move 'daddy' sword had impregnated his little daughter. She gave birth and all but one of the babies were eaten. It wasn't long after that she became a male. One year on he/she is still in the tank with his/her daughter. As far as I'm aware ther have been no babies.

 

[diburning]

ok, the sex changing is due to the chromosones in the genes. All fish of the xiphophorus and poecila type posess X, Y and Z chromosones. When the fish are born, they will be in a 1male:2female ratio since fish born with the Z chromosone are born female then change to males near middle age or during old age.

since the chromosones are paired, some have XX, XY, and XZ. The XX will be female, XY is male, XZ will be born female, then changes their sex later in life.

The sex change is a 1 way process.

This also happens in certain species of clownfish. after mating, the male will turn into a female.

 

[Annastasia]

ok, the sex changing is due to the chromosones in the genes. All fish of the xiphophorus and poecila type posess X, Y and Z chromosones. When the fish are born, they will be in a 1male:2female ratio since fish born with the Z chromosone are born female then change to males near middle age or during old age.

since the chromosones are paired, some have XX, XY, and XZ. The XX will be female, XY is male, XZ will be born female, then changes their sex later in life.

The sex change is a 1 way process.

This also happens in certain species of clownfish. after mating, the male will turn into a female.

As I said in the Molly topic, any proof? I've never experienced it with my Swordtails or Mollies, and seems I should if one out of three is born with a Z and changes.

I'm not doubting, just wondering and looking for proof.

 

[bleechme]

I have been researching and this is the most useful and believeable information I've found so far. But I will keep searching.

"One interesting feature of this livebearer is the apparent ability of the female to change sex and become a male. This is, in fact, simply a late developing male — I have been unable to locate any accounts of females giving birth and then changing to a male."

Credit: http/www.aquariumfish.com/aquariumfish/d...id=3787&search=