She/Male Molly (!?)

[Salvelinus]

History:
4 female and one sailfin male molly in a 55 gallon tank, no other fish
except their offspring which get moved to their own tank. The male is
a bit of a dud in that he occasionally chases and nuzzles the nether
regions of the females, but certainly doesn't try too hard to
impregnate them (however they do have babies with reasonable
regularity). He isn't the typical male though - more show than dough.
One female rules the tank. She's the biggest one (about 3 inches) and
rules by force at feeding time. She's had a few litters, and was very
clearly female.

Now, here's the interesting part... Over the course of the last month,
the big female began to change. Her dorsal fin elongated, and is now
partway in length between the usual females and a male sailfin. Also,
her anal fin is now a gonopodium!! It was definitely a normal female
anal fin before!. She wiggles it like a male would (bringing it
forward, etc.). Behavior wise, she's also now started to nuzzle at the
anal fin region of the other females. Strangely, the lone normal male
still nuzzles at her in courtship displays.

I'm a biologist, and know that the fish can't simply be "changing sex",
but that it might have been a hermaphrodite to begin with (or somehow
had access to some testosterone!). I just find this pretty
interesting, and wonder if others have seen this before.

[Charles]

On 23 Jan 2006 06:58:07 -0800, "Salvelinus" >
wrote:

>History:
>4 female and one sailfin male molly in a 55 gallon tank, no other fish
>except their offspring which get moved to their own tank. The male is
>a bit of a dud in that he occasionally chases and nuzzles the nether
>regions of the females, but certainly doesn't try too hard to
>impregnate them (however they do have babies with reasonable
>regularity). He isn't the typical male though - more show than dough.
>One female rules the tank. She's the biggest one (about 3 inches) and
>rules by force at feeding time. She's had a few litters, and was very
>clearly female.
>
>Now, here's the interesting part... Over the course of the last month,
>the big female began to change. Her dorsal fin elongated, and is now
>partway in length between the usual females and a male sailfin. Also,
>her anal fin is now a gonopodium!! It was definitely a normal female
>anal fin before!. She wiggles it like a male would (bringing it
>forward, etc.). Behavior wise, she's also now started to nuzzle at the
>anal fin region of the other females. Strangely, the lone normal male
>still nuzzles at her in courtship displays.
>
>I'm a biologist, and know that the fish can't simply be "changing sex",
>but that it might have been a hermaphrodite to begin with (or somehow
>had access to some testosterone!). I just find this pretty
>interesting, and wonder if others have seen this before.


As a biologist, you should have heard that some fish change gender as
part of their normal life process. I don't believe that any mollies
have been documented to change to the other sex and be fully
functional, but I have read of them changing external sex
characteristics. I would guess that this particular fish's
reproductive days are over. You are in a good position now to
document what happens.

[Salvelinus]

I'm a molecular geneticist, so I'm aware of the chromosomal
determination of sex. I'm not trained in the life cycles of fish! ;-)

[NetMax]

"Salvelinus" > wrote in message
oups.com...
> I'm a molecular geneticist, so I'm aware of the chromosomal
> determination of sex. I'm not trained in the life cycles of fish! ;-)


We won't hold that against you ;~), but you *will* need to be taking notes
now. If you could isolate a few female Mollys for about 6 months (until
their internal supply of sperm has been exhausted), then introduce 'it' and
if there are any fry born, there could be a article which needs to be
written.
--
www.NetMax.tk

[Charles]

On 23 Jan 2006 09:56:31 -0800, "Salvelinus" >
wrote:

>I'm a molecular geneticist, so I'm aware of the chromosomal
>determination of sex. I'm not trained in the life cycles of fish! ;-)

Most (?) fish follow the normal genetic determination. In the genus
xiphophorus the genes are apparently spread over nine different
chromosomes, and their expresion can be influnced by enviromental
factors.

In many reef fishes, one male dominates a harem of females, if the
male dies, then the largest female becomes male. story at:

http://www.bio.davidson.edu/Courses/anphys/1999/Rice/Rice.htm

The Californai sheepshead, Semicossyphus pulcher, starts life as a
female, then changes to male later. story at:

http://www.dfg.ca.gov/mrd/mspcont7.html

It's an interesting world.

[Gill Passman]

Charles wrote:
> On 23 Jan 2006 09:56:31 -0800, "Salvelinus" >
> wrote:
>
>
>>I'm a molecular geneticist, so I'm aware of the chromosomal
>>determination of sex. I'm not trained in the life cycles of fish! ;-)
>
>
> Most (?) fish follow the normal genetic determination. In the genus
> xiphophorus the genes are apparently spread over nine different
> chromosomes, and their expresion can be influnced by enviromental
> factors.
>
> In many reef fishes, one male dominates a harem of females, if the
> male dies, then the largest female becomes male. story at:
>
> http://www.bio.davidson.edu/Courses/anphys/1999/Rice/Rice.htm
>
> The Californai sheepshead, Semicossyphus pulcher, starts life as a
> female, then changes to male later. story at:
>
> http://www.dfg.ca.gov/mrd/mspcont7.html
>
> It's an interesting world.

Fascinating stuff...

The ex Alpha male in my Malawi tank has lost his egg spots since being
ousted...I was thinking that he was trying to keep a low profile...but
who knows?

[Charles]

On Mon, 23 Jan 2006 18:48:16 +0000, Gill Passman
> wrote:

>Charles wrote:
>> On 23 Jan 2006 09:56:31 -0800, "Salvelinus" >
>> wrote:
>>
>>
>>>I'm a molecular geneticist, so I'm aware of the chromosomal
>>>determination of sex. I'm not trained in the life cycles of fish! ;-)
>>
>>
>> Most (?) fish follow the normal genetic determination. In the genus
>> xiphophorus the genes are apparently spread over nine different
>> chromosomes, and their expresion can be influnced by enviromental
>> factors.
>>
>> In many reef fishes, one male dominates a harem of females, if the
>> male dies, then the largest female becomes male. story at:
>>
>> http://www.bio.davidson.edu/Courses/anphys/1999/Rice/Rice.htm
>>
>> The Californai sheepshead, Semicossyphus pulcher, starts life as a
>> female, then changes to male later. story at:
>>
>> http://www.dfg.ca.gov/mrd/mspcont7.html
>>
>> It's an interesting world.
>
>Fascinating stuff...
>
>The ex Alpha male in my Malawi tank has lost his egg spots since being
>ousted...I was thinking that he was trying to keep a low profile...but
>who knows?


A recent article in one of the aquarium magazines (TFH?) told about a
late male, grew in size until it was larger than the alpha male, then
displayed male characteristics and took over. Sneaky was to avoid
harasment while growing up. One of the livebearers, but I can't
recall the details.

[Gill Passman]

Charles wrote:
> On Mon, 23 Jan 2006 18:48:16 +0000, Gill Passman
> > wrote:
>
>
>>Charles wrote:
>>
>>>On 23 Jan 2006 09:56:31 -0800, "Salvelinus" >
>>>wrote:
>>>
>>>
>>>
>>>>I'm a molecular geneticist, so I'm aware of the chromosomal
>>>>determination of sex. I'm not trained in the life cycles of fish! ;-)
>>>
>>>
>>>Most (?) fish follow the normal genetic determination. In the genus
>>>xiphophorus the genes are apparently spread over nine different
>>>chromosomes, and their expresion can be influnced by enviromental
>>>factors.
>>>
>>>In many reef fishes, one male dominates a harem of females, if the
>>>male dies, then the largest female becomes male. story at:
>>>
>>> http://www.bio.davidson.edu/Courses/anphys/1999/Rice/Rice.htm
>>>
>>>The Californai sheepshead, Semicossyphus pulcher, starts life as a
>>>female, then changes to male later. story at:
>>>
>>> http://www.dfg.ca.gov/mrd/mspcont7.html
>>>
>>>It's an interesting world.
>>
>>Fascinating stuff...
>>
>>The ex Alpha male in my Malawi tank has lost his egg spots since being
>>ousted...I was thinking that he was trying to keep a low profile...but
>>who knows?
>
>
>
> A recent article in one of the aquarium magazines (TFH?) told about a
> late male, grew in size until it was larger than the alpha male, then
> displayed male characteristics and took over. Sneaky was to avoid
> harasment while growing up. One of the livebearers, but I can't
> recall the details.

That's exactly what my Mbuna did....he kept himself quiet in a
cave...and then one day lured one of the females in there...after that
total mayhem broke out until he eventually became the alpha...(Maylandia
Lombardii). He is now absolutely massive - about half the size again of
the original alpha...