What affects gender of fry?

[AndersB]

I breed L134 and I kept 12 fry for my self. Now they are about 6 cm long, and they are all male!?!

Does anybody know what affects the gender of loricariidae (L134) fry? How come all 12 is male?

[Jobro]

Hey Anders,

They all have odontodes on their tails at 6cm?

12 out of 12 males is not impossible but very unlikely. maybe they are not all males, after all?

[AndersB]

Hi

Yes, they all have odontodes on their tails. I also couldnt believe it, but I just had a close look, and all of them have it.

But what can cause that they all became male? Temperature? Ph? Conductivity?

[Bas Pels]

I don't recall reading about male/female distributinopn due to environment in Loricarids

But both in Crocodiles and some Poecilids a few degrees in temperature can make a brood 100 % male.

pH is said to do the same in Apistogramma - high pH producing more males

But Loricarids are NOT Apistogramma, Poecilids or Croccodiles.

[Fundulopanchax76]

Maybe you chose only biggest fry to keep for yourself and that way you chose only males ? Because males are ordinary bigger in earlier age ?

[AndersB]

Bas Pels - but what affects gender in loricariids then?


Fundulopanchax76 - fortunately I am aware of that, so I havent picked the biggest for my self:)

[bekateen]

I have never read of any form of environmental sex determination in loricariids. I don't mean it couldn't occur, but I've not read or seen any evidence for it.

Cheers, Eric

[AndersB]

Ok. The batch that all turned male was hatched at 30 degrees C. I have another batch that hatched at 27 degrees C. They are not that big yet, but I will return here and tell how they turned.

Thanks to you all:)

[bekateen]

Good luck, Anders!

[Fundulopanchax76]

The good thing is that your 134 breed ! Because many people have problems with them !

[AndersB]

Thanks

Yes, they are not always easy

[Bas Pels]

With regard to your information of raising temperature for your first and second batch, did the eggs hatch at the same temperature?

Sometimes there is only a short window of time to determine things. That is - it could be that hatching temperature will determine sex, not raising temperature. after all, in that case after hatching seks is already determined.

I'm not saying it is so, but that makes experimenting so hard: Nobody has a clue what will influence the results and what not.

Obviously the same goes for pH and any other influence you may imagine.

And just as obviously, you will not be eager to do experiments with the adults.

[AndersB]

Bas Pels - true, there are lots of different variables. Only difference in this case is temperature - both in when eggs were fertilized, hatched and first weeks of growing

[Bas Pels]

Thanks, that helps

I've a group of swordtails, which breeds aroud 1/3 male. Their tank is not heated. Now one female was not 100 % OK, and I put her into the largest tank, which is heated, to 4 C, to be eaten.

She was not eaten, but did produce fry, and it looks like the surviving fry are mostly males. Here the food, the pH and so on are also the same, only the temperature - during pregnancy, and raising, was higher.

Now the problem is, can I conclude the warmer water produced this difference? I think the honest answer is I think not.

Fistly, in both cases a swordtail produces some 20 to 50 fry a time, and the group is 10 while in the large tank, after 4 litters, there are some 15 fishes. That is, most of the fry is, in both cases, eaten. I can not say whether these were males of females.

The theory sais that certain genes make the chances of becoming male higher (or lower) but that would imply the sex is decided on a certain time. Who can tell me when this is? At 2 cm I cannot tell them apart, but it could very well be decided.

I could take a lot of impregnated females, putting them @ 18, 21 and 24 C, await fry, and remouve them @ 1 cm, 2 cm and 3 cm, destributing them over 18, 21 and 24 C water. Then I could await what happens, and I might even be so lucky as to have statistically significant results.

Would any significant result have any meaning? I would need 27 tanks, but I only have 9

[AndersB]

Hehe you need more tanks and more time