What Age/size Can You Determin The Sex Of Platy Fry?

[super-MAGuire]

I have 2 generations of platy fry going at the moment, i cant tell the sex of the older generation yet, using the good old ventral fin dimorphism. If theirs any other ways to sex them, or roughly what age would be a good help, i would like to seperate the male and females to stop the breeding esculating!

 

[fluttermoth]

Normally around three to four months, but do be aware that you may get late developing males that can look female for much longer

Anal fin dimorphism, btw; the ventral fins are the paired ones underneath the gills

 

[super-MAGuire]

Normally around three to four months, but do be aware that you may get late developing males that can look female for much longer

Anal fin dimorphism, btw; the ventral fins are the paired ones underneath the gills

yeah, i confused the pelvic, aka ventral with anal fin... anal.... vent.... ventral.... #17##### where they poo out of lol wouldnt think i have a marine biology degree lol

They can live together for another couple of month then, just their coulouration is really coming on strong now. I just dont want an ever exploding platy population, or give a few fish to someone who then has an exploding platy population, although alot of people would think that would be a score!

 

[basboi85]

I have a idea that might be well outside the box but ( I say but )

I'll use Molly's as a example as I have Molly's

I don't know if it's me or does The male Molly anus seem further forward than a females anus ?? I.e the males willy( can never say or spell it) is behind the anus which makes males anus in middle of their stomach instead of being further back on females hense my idea of maybe guessing male/ female fry at early age

I'm probably wrong but as I said its a idea well outside of the box but might be actually true

 

[FishBlast]

I have a 5 month old fry and a 3.5 month old one. They both vaguely have gonopodiums, but still look somewhat like females. -.- Though they are swordtails, it's basically same with them and they are related to platy fry.
You could probably tell the males if they start displaying. I notice display behavior when they are 1 month old.