Sex reversal

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necrocanis

necrocanis

Catfish God
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Oct 10, 2005
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Ok so I have a project that I am getting into and need to know if sex reversal can be done in fish that are past the normal 21 day window after hatching? If anyone has any info on this I am eager to hear it. I know there are many species of fish that will actual sex reverse on their own depending on many variables. There is special feed that hatcheries use to do this, but they do it in the early days within 4 days after hatching they start treatments and go for 21 days after that. So when the fish is a month old it's sex can be determined. I was wondering just how far you can go with this?
 
Where's Phil (Oddball) when you need him. It's to my, albeit very limited, knowledge, that only certain species of fish are capable of such changes. I've heard of hormones being used and that's about it.


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The feed I'm talking about has the hormones in it. You can sex change probably any fish if done early enough, but I'm not sure of the success in fish that are beyond the normal sex reversal period. I'm sure oddball has some knowledge on this subject as well. :) There are also hormone baths that can be used when the fish are young, but what about subadult and adult fish?
 
I have heard of older fish changing genders due to environmental factors. It allows the fish to change sexes based on a need. For example, there is a certain species (can't remember the name), that normally swims in schools of 1 dominant male to 3+ females. When the male dies, one of the females will change to male in a matter of days. That being said, i've never heard of forced hormonal change at an older age.


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I've heard of this one also. :) thanks for sharing. There are many species in a variety of different kinds of fish that can do this. I'm just thinking how much easier it would be to sex and breed fish that have no sexual dimorphism. If you could control the gender. Say pond A would be treated with male hormones and you end up with 10 male fish, and pond B is treated with female hormones and you end up with 10 female fish. Of course this is just an example, and you would end up with some sterile and some hermaphroditic, but you get the point. :) The vast majority would still be the sex you want. Maybe I will write to the company Syndel that manufactures these and other hormones and see what they have to say about it. I will post my findings in here if any so that every can have some new knowledge.

This of course if for breeding fish that are non dimorophic and are not natural breeders in captivity. Could come into play for anyone looking to set up their own small or large scale hatchery for tropical fish.
 
Tnx for the links i will read them in depth later. I have been doing a lot of research on this. I may need to contact some tropical fish hatcheries as well as it seems most try to produce all male fish for their bright colors on most species. Very hard to find any literature on sex reversal in fish that are beyond the first month of developement.
Drstrangelove said:
http://www.dfw.state.or.us/fish/OHRC/docs/2010/Sex Reversal in Hatchery steelhead - Thompson.pdf

http://www.fao.org/docrep/field/003/ac182e/AC182E01.htm

http://maxwellsci.com/print/ajfst/v3-144-154.pdf

http://www.panoramaacuicola.com/int..._genetic_strains_and_hatchery_technology.html

Try this.
Click to expand...
 
I guess i wont really need this for my first project but id anyone comes up with anything it qill be helpful when i get to the harder species. :)

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