Changing sex - inka 50

[blueblue]

In the following URL (from Taiwan),
http://aqua.andy.idv.tw/viewtopic.php?t=51781
we can find a photo of a male Inka 50 (the 3rd picture),
according to the owner of the fish, it was originally a
female fish which had laid eggs and kept fries for some time!! ...
As shown in the picture, it looked like a fish transformed from
female to male, too...

Moreover, in the same chinese forum, another man
mentioned that his aggie also got similar experience: i.e.,
female mother fish (with eggs and fries) became a male fish...

Are there any other recent reports on this topic??

 

[cageman]

if this story is true which I doubt, it is good news for me.
I have 4 females swimming at this time. maybe one of them decides to be male

 

[Mike Wise]

To be a true sex change the fish must be fertile as both sexes. Koslowsi (1986) reported a sex change in A. sp. Cheek-spots/Wangenflecken in which the fish laid eggs & produced viable fry. Then it changed sex and fertilized eggs that produced viable fry. This is the only known true sex change reported. I imagine that it can happen in other fish, too.

 

[blueblue]

i used to be doubtful on these "stories"... however, more and more
evidences have appeared from all sources. Some come from highly
reputable friends and experts...so, i am now more willing to accept
these cases ...

 

[blueblue]

To be a true sex change the fish must be fertile as both sexes. Koslowsi (1986) reported a sex change in A. sp. Cheek-spots/Wangenflecken in which the fish laid eggs & produced viable fry. Then it changed sex and fertilized eggs that produced viable fry. This is the only known true sex change reported. I imagine that it can happen in other fish, too.

Hi Mike: Thanks for your expert comments;
well, the case reported in the chinese forum that i posted was similar to the case you mentioned above: A female inka 50 laid eggs and produced fries with a male inka 50 fish. It then became a male and fertilized another female and produced fries... i guess if the owner of the fish didn't tell lies, then it's a very strong and scientific evidence for proving the ability of changing sex in Inka 50...

 

[Rolo]

if this story is true which I doubt, it is good news for me.
I have 4 females swimming at this time. maybe one of them decides to be male

Well, you need a little bit luck for that ;-)
Römer ("Das Aquarium" (06/04)) wrote, that sex-change is "not rare" in the A. nijsseni-Komplex... about 1 : 1-2000. So with your four females it could be a little bit difficult ;-)

@Mike: Römer also wrote, he knows two cases of "sure" sex-change, but he didn't mentioned the second one. Sure, Koslowski is one of them.

greetings,
Rolo

 

[blueblue]

Hi Rolo, thanks for the interesting sharings;
i just wonder what it exactly means by 1: 1-2000? Does it mean that the chance can vary from 1 (i.e. 1/1) to 1/2000? How did Romer calculate this ratio? Are there any english articles talking about it? (I could not read german though i am a big fan of the bundesliga ... )

 

[Rolo]

i just wonder what it exactly means by 1: 1-2000? Does it mean that the chance can vary from 1 (i.e. 1/1) to 1/2000?

No, I think, it means: on an average of 1000-2000 females will be one, that changes sex. (but that also include, that you can have a sex change at 1/1 *g*)

How did Romer calculate this ratio?

I don't think, he calculates or counts that number ;-) ... it's probably more a guess.

Are there any english articles talking about it? (I could not read german though i am a big fan of the bundesliga ... )

It's unfortunately the only one I know. ...and I mostly prefer to read german articles, though I'm not such a big fan of the Bundesliga. But it was a pretty good party last year, when "we" (I'm from Bremen) became german champion against Bayern (our all-time-enemy *g*)

greetings,
Rolo

 

[blueblue]

Thanks Rolo. i see, and i am still thinking of how Romer estimates the
chance... i think there're some estimations as he is not just giving
a wide guess of 1: 1000, but he gives a range...

Bremen is a good team while I am a big fan of FC Bayern

 

[tjudy]

I have witnessed sequential hermaphroditism in Dicrossus filamentosus.

 

[aspen]

ted, i have no doubt that you have seen it. but from your statement, how could one establish 'scientific proof? or this other fellow who claims he has seen it?

rick

 

[Mike Wise]

I don't know about Ted, but Koslowski's observations are very clear. He had a pair in a breeding tank that produced viable fry. He then lost the male. The female was put in with a smaller female. Over a few month the older female developed masculine secondary sexual features: longer dorsal and anal fin tips & a blue sheen on the scales. The 2 fish produced viable fry that were guarded by the smaller fish. Unless the species are isolated so that there can only be 1 male & 1 female, then there can always be questions of who is the father.

 

[tjudy]

I started with a group of juvinile Dicrossus that were unsexable, and separated them into groups of five in ten gallon tanks to grow out. They were so small that I was nto even sure which species they were... I was hoping for maculatus. As the fish started to show sexual dimorphism I separated the males from obvious females. I paired up three males with females in their own tens, the each pair produced spawns. The eggs would hatch, but the fry did not survive... I did not have RO/DI at that time.

One of my breeder males died, and I did not have another male, so I placed three other females that were all smaller than the breeder female in the tank with her. Over a period of about three weeks I watched that larger female turn into a male. 'He' then paired with the next largest female inthe tank and started to breed, again producing eggs that would hatch. I then went an purpsofeully removed a male from another breeding pair and replaced him with three smaller females, and I saw the event happen again.

One of the key elements, I think, is that I started with a group of fish that were all unsexable juviniles in the 3/4 to 1 inch size range. Most of the Dicrossus we see are imported adults.

I would love to try it again, especially now that I can probably match water conditions better, but I have not come across a group that are that young.