DNA Sexing

[Attila]

I'm thinking outside the tank a little bit...



There are many laboratories that DNA sex birds (mostly parrots with no sexual dimorphism) using a feather or blood sample. It's not even that expensive...around $20. They send you a little collection kit, you collect the sample, send it back, and they perform PCR (or perhaps even sequencing if you want to get fancy) to determine if the specimen is a male or female. Why not for discus?? Can you imagine how useful it would be to know the sex of your young discus before they pair off?

Has anyone else ever thought or heard of this?

I'm going to do a little more research and report back if I find anything.

[Attila]

I may have hit a snag... I don't think the Symphysodon spp. genome has been sequenced, so the markers for sex may not yet be known for discus.
I'm still researching, though!

[Discus-n00b]

You could just do an Andrew Soh CHOP CUT and figure it out easy!

[John_Nicholson]

Personally I don't see much use to this. If you pick your small fish properly you will get a mix of males and females anyway. I don't really think knowing ahead of time will make any real difference.

-john

[timmy82]

Yeh John very correct why go trying to minipulate nature? I find it better to learn how to pick by looking and see how you go.

[Attila]

Thanks for the responses!

Personally I don't see much use to this. If you pick your small fish properly you will get a mix of males and females anyway. I don't really think knowing ahead of time will make any real difference.

-john

How do you pick properly? By getting a large enough number of fish?

Yeh John very correct why go trying to minipulate nature? I find it better to learn how to pick by looking and see how you go.

It could be argued that here are a lot of things in this hobby that "manipulate nature." For example, I don't think Blue Diamonds and Pigeon Bloods just naturally evolved in the Amazon. However, I don't think that finding out the sex of a fish qualifies.



I contacted a couple of laboratories that do this type of testing; and none of them are able to do it for fish yet.
...on to the next crazy idea haha

[John_Nicholson]

Starting with 6 will give you about a 88% chance of getting a pair. Getting 10 you should get 2-3 pairs. People mess up when they go look at a 2-3 inch spawn and try and buy all of the biggest ones. Guess what you probably got mainly males. Look at a spawn and pick the 2 largest/nicest ones. Then pick 4 nice medium sized ones. You will not have issues getting pairs then. As far as picking them out as adults...it is more of an art than a science. You just have to look at a lot of pairs before you understand.

-john

[Attila]

That all makes sense, John. Thanks!

I hope to get some practice looking at pairs soon! I've been researching the sponsors on here before deciding from whom I should buy a pair. I'm almost ready to make the jump!

[dr.cichla]

Hi guys/gals: I agree with everything John said, for general practice. That being said, I can imagine wanting to know the sex of a show-winning fish that is resistant to pairing and spawning, just to know what other kind of fish to help entice him/her.

The problem is that, unlike birds, which are all heterogametic (the males and females have different sex chromosomes, in this case ZZ and ZW respectively, like mammal XX/XY but backwards), the chromosomes of all cichlids (as far as I know) are all equal in gene compliment. And, as was mentioned, there is no genome sequence for discus (although there are Africans, which would be close enough for many things) and no known sex genes. To top it off, among many cichlids and related fishes, gender may not be entirely genetically determined, so even knowing certain genotypes may not provide the correct answer. It wouldn't be that terribly hard to make some significant headway here, but nobody with the expertise is interested in doing it because it's not high enough impact to justify renewed funding.

Not satisfied with the state of research in this area? Tell your legislator to vote to increase funding for basic science.

Stu Willis