Sex Changing Fish

[helterskelter]

Hi DG John's book is like a bible to me, had it scince it first came out around 15 years ago.

Like I've already stated their is no scientific papers that i have seen or heard of to back sex reversal in Poeciliidae species.

How ever the Poecilia formosa (Amazon molly) is a special species that's totally female in population.
The females need to breed with other species to produce fry, however the eggs are already diploid which means that they already have the complete DNA make up and the male's DNA it rejected, how ever on occasions the males DNA is not rejected causing whats called a triploid. These triploid's are males but they are very rare and not needed for the species.

 

[Lynden]

In Lynden's case, for this to carry scientific weight, he would need to prove that his female was a genuine female. Saying "I am experienced and I know what a female looks like" is not scientific proof. Looking for sex chromosomes is not an option, dissection is not an option- he would really need to show that this individual female had given birth (on its own, not with other females who might be the real mother) and then turned into a male, i.e. a fish that was able to impregnate other virgin females. As far as I know, the situation is still the same as when Dawes wrote: noone has carried out these experiments under sufficiently controlled conditions.

I didn't intend that to be a rock-solid scientific study, I was merely explaining my experience regarding the subject.

The guppy was a virgin female, and though I did see it mating with the remaining females, none of them lived long enough to actually give birth (as stated above, they were used as target fish). So I suppose it may have not been a "real" case... though that female that did change was definitely an adult and nearly full-grown.

 

[helterskelter]

So how old was the guppy then when she turned male?

 

[Lynden]

I'd say about a year or so... About 1.5'' in length.

 

[helterskelter]

It's been noted that some late devlopers have turned at around 8-10 months, so 12 months is the olderst male I've ever heard of.

Was it with many other males?

 

[GobyMaster]

That'd be awesome to have a fish that could change it's sex! Then you could name it Michal Jackson!
Maybe you could teach it the moonwalk (swim??)
Sorry, seeing this topic I just had to do it.
Cheers,
GobyMaster

 

[jourdy288]

I remember reading from Herbert Axelrod a book from the 80's, where it explains female swords becoming males, but theyr'e not functional.

 

[Lynden]

I've read that too. To answer the above, no 'it' wasn't with any other males.

 

[KingofthePisces]

i know that the australian barramundi changes from male to female when they reach a certain size

 

[KraKen]

Clown fish have a sex based social structure, when the alpha female dies the alpha male changes sex and takes her place, then the beta female takes the place of the alpha male and so on and so forth...

 

[Synirr]

A few days ago I was reading a paper dicussing the social rearing issues with transgendered human babies. It was discussing how for a child to become male, not only must the Y chromosome be present, but the hormonal levels and development must be complete and proper for the fetus to develop male genitalia. The argument presented, was that 'male' children born with incomplete genitalia can actually be forced to revert to females by removing and altering the genitalia so the hormonal levels are changed. This will actually allow the child to pass through puberty as a female (aka menstruation) and it will proceed to be a functionally reproductive female. The point of the paper was the belief that Female was the base sex and that to become a male required specific hormonal attributes that could potentially be developed.

It would be impossible for a physically male child, born with incomplete genitalia, to go through puberty as a female unless a uterus or partial uterus were present, in which case the child would never be considered male in the first place, but instead intersex. One cannot menstruate without a uterus, and one cannot spontaneously develop one after fetal development is complete. Ovaries are a requirement, and if a child develops with testes that child simply will not become a "normal" female. A child without any reproductive organs will develop more-or-less female though, physically speaking, but will never reach proper puberty without ovaries, testes, or some mix of the two (hey, it happens. :shrug

Interestingly, only a small section of the Y chromosome codes for "maleness". If that section is mistakenly deleted, or swapped with a section of X chromosome during recombination (it's not supposed to happen, but sometimes does; only analogous sections are supposed to be swapped), a child can have XY chromosomes but still develop as a female. The child will most likely be sterile, like a typical XO female, but there you are. Alternatively, what happens if a child gets that X chromosome that picked up the maleness coding section the Y lost during recombination? That child would be genetically XX, but still develop as a male.

 

[helterskelter]

But all this has nothing to do with fish though. Fish are very different and many thing's are possible the thread on a killifish the other day has shown another line.

This some info i found on it

The mangrove killifish or Rivulus marmoratus Poey, 1880 has been documented for many years due to several amazing facts like it's a self-fertilizing hermaphrodites. The gonads of R. marmoratus are actually ovotestes that produce both eggs and sperm. and now it live's in trees...... i must be going mad!!!

Original post

Note ovotestes which allows the on fish to produce both eggs and sperm, I've seen this personally on some trout, how ever in most species that are not meant to be like this they are usually infertile as the tubes usually from the testie are missing (this is the same in triploides).

 

[Squidman]

sama: Weird