How To Influence Sex Of Fry

[gizmo001i]

Hi,
My wife has been breeding guppies for the last 6 months but has found that there are more females than males. She has heard that there may be a way to influence the ratio of male/female fry being born. Is this true and if so what would she have to do to increase the amount of males born. Your help in this will be very appreciated.
Many thanks
Ian

 

[guppykid2006]

i dont think there is a way. its kind of like trying "different positions" ( trying not to be gross) to get a boy. it dosnt work.

 

[confusion]

seeing as how the fish apparently do better when there are more females than males, it's not suprising that broods come out more heavily female.

 

[demonmagus]

I *think* pH has got something to do with it

 

[The-Lion]

I was told by the fella at the lfs that the a higher water temp would result in more male fry when i brought Endlers, but there was those on here who disagreed when asked but have also read ph can influence things.

 

[diburning]

it has to do with genetics.

Most common livebearers have X,Y, and Z chromosones. Z is a special chromosone. Z is female (for most of its life... I will explain later)

so the ratio is 1 male to 2 females.

the chromosone types would be: (XY: male, XX/XZ: female)

Ok now about Z chromosones.

The Z chromosone exists in most livebeaerers such as mollies, guppies, platys and swordtails. Rare livebeaers don't seem to have it.

When a fish is born, the sex is unknown until it rechaes sexual maturity.

A fish with a Z chromosone is female in the most part of its life. During middle age, she may turn into a male. This is highly unlikely to happen during middle age however...

In old age, the female with the Z starts getting a gender change and turns into a male. These "males" are usually sterile (sometimes they can still breed) and they will live their lives as males until they die.

 

[BitterCowgal]

This has been discussed a couple other times...

http/www.fishforums.net/index.php?showtopic=149346

http/www.fishforums.net/index.php?showtopic=128142

I'm still waiting to see the results of my High Temp/High PH raised fry to check the theories.