26-02-2024, 10:07 AM
From another thread where this was off-topic....
Oh_hunnihunni Wrote:
"You had me intrigued with the gender changing thing, but it seems more likely that apparent sex changes are in fact just late developers, though hermaphrodite fish are occasionally seen. They are usually sterile though, so I think I can just focus on the youngsters who start showing male colouration and separate them out till I can select the best one to go back with the females. "
There are a number of fish that routinely change sex as part of their normal life cycle, eg clown fish, spotties, etc. Here's a general article about it https://www.latrobe.edu.au/news/articles...change-sex.
For guppies, when you do a Google search you get lots of fishkeepers on forums asking the questions related to what they have observed and "experts" coming in saying guppies can't change sex/gender. And you will get an occasional person saying "no, that is wrong" but most of the links they provide are old and gone.
I think the explanation that I have always gone by came from the book Sex, Color, and Mate Choice in Guppies by Houde. I had interloaned the book through my library so don't have it at hand, and Google Books doesn't provide the preview of the right chapter. It was a long time ago (my notes show 2009) so I might be remembering the wrong book. Anyway, what I have always understood is that guppies have XX/XY genes like we do and that when there are no males present (eg in the wild they have been eaten by a predator – they are smaller and more prominently coloured than the females after all) the population can continue by male hormones being triggered in a female so that she can breed with the other females and produce babies. The babies are all XX (ie female) and any that function as male will be less colourful than XY males because many of the guppies' colours are Y-chromosome linked. But it's a temporary survival strategy that helps to prevent extinction until the all-female group gets a chance to meet up with a normal group with access to males again.
It's rarely seen in hobby fishkeepers because no one really keeps groups of females on their own. Usually a tank of sexually mature females will have male fry with them, or already be fertilised by a male from the past (one insemination can last for months worth of broods - the more common "population survival" strategy). So usually when people think they have observed an apparent sex change it is mistaken, but it is occasionally seen. Usually the gravid spot disappears as any developing embryos are reabsorbed, but if the change is late enough in their development a "male" can give birth. Somewhere along the way I have seen a photo of a fish with a gonopodium giving birth.
There are also all sorts of stories about the trade practices in Asia, where most of our imported fish come from, that include a few weeks of use of (reversible) synthetic testosterone to get females to show their genetic colours to facilitate line breeding, and also the practice of somehow manipulating XX-only fish so that the fish bought by the customer are sterile. I have no idea how true that is.
The great thing about your Endlers is that, unless they have been hybridised with guppies, they will be a "pure" population. I have no idea if they can change sex, but surmised that it might be possible because they are so closely related to guppies. Not a worry for you though. You can just sit back and enjoy them so long as you have a means of controlling the numbers, which is what you are doing. Have fun.
Oh_hunnihunni Wrote:
"You had me intrigued with the gender changing thing, but it seems more likely that apparent sex changes are in fact just late developers, though hermaphrodite fish are occasionally seen. They are usually sterile though, so I think I can just focus on the youngsters who start showing male colouration and separate them out till I can select the best one to go back with the females. "
There are a number of fish that routinely change sex as part of their normal life cycle, eg clown fish, spotties, etc. Here's a general article about it https://www.latrobe.edu.au/news/articles...change-sex.
For guppies, when you do a Google search you get lots of fishkeepers on forums asking the questions related to what they have observed and "experts" coming in saying guppies can't change sex/gender. And you will get an occasional person saying "no, that is wrong" but most of the links they provide are old and gone.
I think the explanation that I have always gone by came from the book Sex, Color, and Mate Choice in Guppies by Houde. I had interloaned the book through my library so don't have it at hand, and Google Books doesn't provide the preview of the right chapter. It was a long time ago (my notes show 2009) so I might be remembering the wrong book. Anyway, what I have always understood is that guppies have XX/XY genes like we do and that when there are no males present (eg in the wild they have been eaten by a predator – they are smaller and more prominently coloured than the females after all) the population can continue by male hormones being triggered in a female so that she can breed with the other females and produce babies. The babies are all XX (ie female) and any that function as male will be less colourful than XY males because many of the guppies' colours are Y-chromosome linked. But it's a temporary survival strategy that helps to prevent extinction until the all-female group gets a chance to meet up with a normal group with access to males again.
It's rarely seen in hobby fishkeepers because no one really keeps groups of females on their own. Usually a tank of sexually mature females will have male fry with them, or already be fertilised by a male from the past (one insemination can last for months worth of broods - the more common "population survival" strategy). So usually when people think they have observed an apparent sex change it is mistaken, but it is occasionally seen. Usually the gravid spot disappears as any developing embryos are reabsorbed, but if the change is late enough in their development a "male" can give birth. Somewhere along the way I have seen a photo of a fish with a gonopodium giving birth.
There are also all sorts of stories about the trade practices in Asia, where most of our imported fish come from, that include a few weeks of use of (reversible) synthetic testosterone to get females to show their genetic colours to facilitate line breeding, and also the practice of somehow manipulating XX-only fish so that the fish bought by the customer are sterile. I have no idea how true that is.
The great thing about your Endlers is that, unless they have been hybridised with guppies, they will be a "pure" population. I have no idea if they can change sex, but surmised that it might be possible because they are so closely related to guppies. Not a worry for you though. You can just sit back and enjoy them so long as you have a means of controlling the numbers, which is what you are doing. Have fun.