Gender switching in Boesemani Rainbow fish

That's so cool, thank you for sharing

Rainbowfish don't change sex.

All young rainbowfish (including Melanotaenia boesemani) look like females and don't develop colour until they are at about 6 months old, sometimes older depending on how well they are grown.

As for the information in the first post which says they change sex due to the presence of a dominant male, what a crock. In fishes that can and do change sex (rainbowfish are not in this group), a dominant male will prevent females from turning into males.

Wrasses, leatherjackets/ triggerfish, some marine angelfish and I think Anthias, can all change from female to male if there is no male around to control the group. Wrasses and leatherjackets live in groups of females with one dominant male who has a territory and controls the group. He intimidates the bigger females to stop them turning into males. If they turn into males they will compete with him and potentially take over his harem.

Anemonefish (clownfish like Nemo) are males and when one takes over a territory (an anemone), it turns into a female and rules the area with a smaller male, and they keep all other anemonefish in the territory as subordinates. If the female dies, the dominant male turns into a female and the dominant subordinate becomes the new breeding male.

Barramundi all start out as males and when they reach about 18 inches in length, they turn into females.

In freshwater fishes, female swordtails can turn into males if there are no males present for a long time (6 months or longer). Most other freshwater fishes do not change sex.

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The OP mentions getting 6 red rainbowfish last week. These are presumably Glossolepis incisus. If all of those fish have red colouration, they are all males. Female G. incisus have no red colour at all. And like other rainbowfish, juvenile G. incisus look like young females and are basically silver all over. As they mature the males go red and the females develop a bronze colour.

The following link has information on all the know species of Australian and New Guinea rainbowfishes and might be of interest to the OP.

Colin, the species is called Red Rainbow. That is not to say all are red. They display sexual dimorphism. I have both male & female reds, G. Insicus. The difference is obvious.

I am reading from credible sources 450 species are known to switch gender, an easy google, however all species are not listed and Boesemani is one. I asked that bot Bard for references and got 3 books mentioned
I could easily find one and will continue to search for the others. I will also pursue other sources. I think what Bard said may be correct. But possibly not.

The information you are getting from bard is wrong. I'm not sure if Dr Axelrod is Herbert R Axelrod, the author and former owner of TFH publications. If it is, anything he writes should be taken with a grain of salt. For a start, Melanotaenia boesemani comes from New Guinea, not South America. I know Dr Gerald Allen and he is an ichthyologist who used to be in charge of that department in the Western Australian museum, and he reclassified rainbowfish back in the 1980s. He has collected most species of New Guinea rainbowfish. I also used to have a number of Gerald R Allen's books on rainbowfish.

I have never heard of Dr Richard B Peter or Dr James Endler and I spent a lot of time in the pet industry and I specialised in keeping rainbowfish for over 20 years. I also collected fish books and don't recall their names on any books. So unless Dr Axelrod, Dr Peter and Dr Endler have some experience with rainbowfish, I would suggest you disregard what they have to say.

I can't find any of those books or 2 of the Drs (Peter and Endler) online. That makes me suspicious of the site you are getting information from. If you have links to those books or an ISBN for them, that would help.

The link I provided above is written by Adrian Tappin, who specialised in Australian and New Guinea Rainbowfishes for many years and even kept them before they became readily available in pet shops. He and a few other people from Australia are the ones responsible for making a number of rainbowfish available to the average person, and providing information on how to keep them. Adrian Tappin is one of the most knowledgeable people in the world when it comes to rainbowfishes from Australia and New Guinea. He knows more about them than I do and that is saying something.

Colin_T said:

In freshwater fishes, female swordtails can turn into males if there are no males present for a long time (6 months or longer).

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This goes for both Xiphophorus species (swordtails and platies). But swordtail females (XX sex chromosome combination) can only change gender when they're of the Aa allele type. And an XX female of the AA allele combination remains female. Aa females are born with both female and male gonads but will always start off as being female. Specimens of the XX sex chromosome combination with an aa allele combination are males despite of the fact that they're not XY males.
In breeding forms of the Xiphophorus hellerii, there are also specimens that can be a WZ or ZZ genotype. It's unclear if the WZ and ZZ genotype also occurs in other swordtail species than just the X.hellerii. Swordtail females of the WZ and ZZ genotype are also able to change sex.

In platies, we're dealing with three sex chromosomes instead of two. Besides X and Y, platies can also have a W sex chromosome. The combinations WX, WY and WW genotypes will be female with both female and male gonads and will always start off as being female. Initial males however can only be of the XY and YY genotype.

When it comes to breeding forms of platies and swordtails, it's a bit hard to determine wether a female will change sex according to the way how swordtails change sex or how platies change sex. This is because of the fact that most breeding forms of both platies and swordtails are hybrids between these two species.

Colin has stated that a sex change can take place if there are no males present for 6 months or longer. But actually, it can also change way before those six months. There are two ways that males will develop when there are no males around or far too few males around in comparison to females. In that case, young initial males will develop their male characteristics pretty fast and those males remain significantly small in size. Such males are called early males. And it can trigger a female to become a male (as long as it's not an AA allele genotype). Both ways are needed to ensure the survival of the population.

When a female platy or female swordtail changes into a male, she'll still have her gravid spot. But she won't produce any eggs anymore. She'll become a fully functional male.

What you're also able to see in Xiphophorus species is that a male can develop a pseudo gravid spot. In swordtails, it doesn't happen that often but in platies it does happen frequently. If a pseudo gravid spot develops in a male, it will mostly develop when they're juveniles. Once such a pseudo gravid spot shows up, it will never fade.
The difference between an actual gravid spot and a pseudo gravid spot is that an actual gravid spot is a piece of translucent skin. It only appears darker in comparison to the rest of the skin because we see what she's got internal shining through. A pseudo gravid spot however is just a dark spot that appears in the skin itself (so, there's no translucent skin in the vent area).

I have assembled a list of articles in academic journals by contemporary researchers and will email all. I’m fairly confident some will reply. Perhaps they will spank Bot Bard or verify it.

I better not post what I’m thinking .

Back in the fold said:

I better not post what I’m thinking .

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You would not offend me. I am not Bard’s developer

So I heard bot ChatGPT does better than the Google bot, Bard, in some cases. So I asked this bot the same questions & it had a very different response, basically the opposite of Bard’s. Since Bard was my first bot, I fell down on the floor, sobbing uncontrollably. This made the dogs and cats howl. The neighbors called 911. I was finally subdued by fire hoses.

Back in the late 1990s I think it was, someone did research on the size of baby rainbowfish when they hatched from eggs. Part of their research including seeing what sex the babies were. They found the fry were separate sexes when they hatched and male fry were slightly bigger and had bigger mouths than female fry from the same batch. They tested a number of species and got the same results for all species involved.

Software on the web that is used to provide answers to questions is not necessarily accurate or up to date. It has been put together by a program that is often made by people who have little to no knowledge of the subject in question. If you want to know about a particular subject, talk to the people that know the subject and read up to date books on it.

The following links are from various rainbowfish groups around the world. There is a guy in America called Gary Lange who regularly collects (or used to) rainbowfish from New Guinea and took the fish back to the states where he bred and sold them. The last I heard had a rainbowfish Facebook group, but if you are in the USA, you might try googling him and contacting him for more information. The last link is a YouTube video of Gary Lange's fishroom and was taken by another person.

I love Gary Lange I wish he was my grandad

Colin_T said:

Back in the late 1990s I think it was, someone did research on the size of baby rainbowfish when they hatched from eggs. Part of their research including seeing what sex the babies were. They found the fry were separate sexes when they hatched and male fry were slightly bigger and had bigger mouths than female fry from the same batch. They tested a number of species and got the same results for all species involved.

Software on the web that is used to provide answers to questions is not necessarily accurate or up to date. It has been put together by a program that is often made by people who have little to no knowledge of the subject in question. If you want to know about a particular subject, talk to the people that know the subject and read up to date books on it.

The following links are from various rainbowfish groups around the world. There is a guy in America called Gary Lange who regularly collects (or used to) rainbowfish from New Guinea and took the fish back to the states where he bred and sold them. The last I heard had a rainbowfish Facebook group, but if you are in the USA, you might try googling him and contacting him for more information. The last link is a YouTube video of Gary Lange's fishroom and was taken by another person.

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www.regenbogenfische.com

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Thanks, Colin. I am in the FB rainbow fish group and we have members from all over the world. I am fairly certain someone there told me to message Gary Lange & from that I assumed he was a group member who rarely posts. I didn’t even bother looking for the guy. What Bard,Google AI said, so far as i can presently determine, had correct info about another species, not BoesemonI. The ChatGPT was far more accurate. The more I questioned Bard, the more absurd his replies became. Laughable. But he is nailing it on medical topics and was correct on other species. I learned much as a result of Bard’s errors, like 450 are known to switch genders. I don‘t why this comes as such a shock. My own cousin switched from a natal female to a male last year.

Yep, that dude is on Facebook, but not in the Rainbow group. Some guy in our FB Rainbow group who is from Singapore told me to message this Gary & he will most likely reply. But I have already found the answers I need for now. I’m glad you informed me he is an expert; initially I assumed he was just another FB guy in our group. I will message him in the future should the need arise.