does temp determine sex of platy fry

[emma12321]

Hi,

I'm new to keeping platies this year. I was given a red micky mouse platy with other various tetras when my boyfriends brother got rid of his tank and as he was the only platy i got him 3 females. I caught 3 fry from the first batch and one managed to avoid being eaten in the main tank

The ones i caught were put in a breeder net for 2 weeks then put in a 2 gallon with a sponge filter and heater. The one left in the tank is female the other 3 male. The males have all moved to another tank now as i didn't want inbreeding.

At the minute i have 13 teeny fry in the 2 gallon so it will be interesting to see what sex they turn out. The main tank is supposed to be 25 but temp is 29 at the minute. The small tank seens to be staying at 25. As soon as my 15 gollon is moved from my mums to my house this will become a fry tank.

Just curious if anyone else has found that temperature makes a difference.

Emma

 

[fawnmodel]

I don't know but I will tell you this, my tanks can never be what I call 'on the low side' of the thermometer. We live in a desert climate, and I often wonder about all the low tank temps I see posted.

My tanks don't go below 27/81 often and usually sit about 82 or so. This is because it is SO hot in the summer even with air conditioning in our house it is that hot in our home at least. So the fish live in it. The thermometer really only operates in the winter, preventing drops.

But all my fish hvae been fine with it, we use good filtration and lots of air. Obviously nearly everyone in my town would have the same issue, cept those with arctic air conditioners, and the bigger shops that stay cool.

BTW my smaller tank is acryllic, for some reason it is always a degree or two warmer than the larger, glass tank

 

[emma12321]

Does anyone else have any oppinions on this subject?

 

[bball4life]

well I have read that people claim that the temperature does do something with the sex, but who knows ?

 

[Tokis-Phoenix]

No temperature does not define the genders of livebearer fry at all, it would be like me going to when you want to have a baby and saying "if you stay in a room at 30degrees for the next 9months your baby will be a boy!", which would basically be very silly.
As soon as the fry are half way through their time being in their mums womb, their genders have already been chosen and it is down to genes rather than tank temp.

In the majority of batchs of livebearer fry, you will always get more males than females as this how they have evolved- in the wild, the more males there are to fight each other over the females when trying to father offspring, the more likely the surviving males will be the strongest and fittest an also the bigger the selection of males the females will have to chose over each other to father their fry.
As much as it seems a pretty random process to us, if there is more than one male in the tank the females will chose the strongest and fittest male and will even go so far to chose the ones that are the nicest to them throughout their previous pregnancys and ate the least of their fry and didn't harrass them too much.

It is posible to have all-female or all-male batchs of fry, but these are very rare on the whole.

 

[William]

Quite a few species have temperature dependent sexual determination, in particular reptiles. Whether this is the case for livebearers I don't know, but it is more than possible since fish do not have distinctive sex chromosomes such as mammals which have the (x and y) that, temperature and pH which have a documented impact on some fish, could well be also be influencing factors for guppies and other livebearers. I think that it is unlikely that the determination of their fries gender is completely random.

So if you have several tanks you could always run a test and let us know how you get on.

 

[MAM]

I believe someone, think the name was guppymonkey, posted a thread about this very topic some time back. I can't recall is he gave links to studies, or if it was based off his own experiences, but something you might want to search on. Be interesting to read if anyone finds out some definite answers.