Sexing livebearer fry

[appaloosatb]

When is the earliest you can tell which gender guppy and swordtail fry are? I have three 1-2 month swordtail fry and about 20 two week old guppy fry and would like to know which sex they are. Obviously, they're too little to be developing the tail colors or swords that help distinguish between them, but I was wondering if I would be able to tell by looking at the anal fin at this young of an age? The swordtails all look to have the triangular female anal fin, while the guppies are hard to tell yet but all look pretty female (they're so tiny I could only check the ones that were very close to the front of the tank).

The reason I'm asking is that the LFS can only take so many livebearer baby "donations" at a time, and if I have any male swordtail or guppy babies I can use them as cichlid treats while they're still little, but they'll be getting past bite size pretty soon.

TIA

[kveeti]

Do you have a magnifying glass? I like this site for guppy info (this is right to the FAQ page): http://guppyplace.tripod.com/FAQS.html
Question 5 tells how and says you should be able to tell the difference in guppies at 1 week, but I'm not so sure, my eyes must be bad, LOL....

[rockhead44]

I agree about one week for the guppies.

[goldfries]

i think it's no harm to wait 1 month later. :p

[thom336]

i must ask u not 2 use live fish as food, as this is cruel practice. how would u feel if ur neighbour fed their young chicks to their dog?

[Faramir]

Originally posted by thom336
i must ask u not 2 use live fish as food, as this is cruel practice. how would u feel if ur neighbour fed their young chicks to their dog?

Anybody selling hot dogs and popcorn? I like nibbles whilst watching a good flamewar....

[JamesBenjamin]

My swordtails had babies, and we were thinking that we should get a oscar to feed them to.

What happens when you feed your catfish shrimp pellets? THEY'RE DEAD SHRIMP!

[clayt101]

I was under the impression that they all start as females until hormones force some to change into males (I am not sure about this). All I know is that everytime mine have babies, mine end up all being females, even with 30+ fry. BTW, this is after they have even aged 6 months. (Also, my experience is only with swordtails):)

[wetmanNY]

clayt101's right on the money! We mammals are male or female right from the moment the egg is fertilized. We have a sex-determining chromosome, the Y that makes us all XX or XY. Or XXY, but let's not get into that eh...

Birds developed a similar program independently.

Fishes and amphibians are indeterminate till approaching maturity triggers some hormonal changes. That's why Singapore fishmills can produce "all-male" shipments of gouramis: they juice them with methyl testosterone.

I don't think the Goddess herself could tell a male from a female at ten days.

[thom336]

the pH and hardness of water can in fact determine the sex of livebearer fry. this is how commercial breeders breed so many of the colourful male guppies in comparison to the less colourful females. this is what could be happening with ur swordtails clayt.

[rockhead44]

thom336
Can you tell us more about this?I have never heard of such a thing.Give us the details.Thanks

[clayt101]

Yeah, is there any more info on that. If thats the case, I could seperate my babies in the future so that I will have different sexes.

[thom336]

the pH and hardness only affects the livebearer young BEFORE they are actually born. i think that harder water produces more females, which is useful in their natural habitat of hard water so that the amourous males do not out number the females. if you wish to produce more males, then soften the water that you are breeding the livebearers in, but not too much - keeping it within acceptable parameters.

[appaloosatb]

Perhaps that's why I have so many girls... my town's water is 8.2 out of the tap, and the PH in my guppy tank is around 7.8.