Baby Guppies

[Ardvark]

Somehow we managed to get a female with some of our new intake. Now we have had babies everywhere. I've put her and most of the babies in another tank. How old do babies have to be before they start breeding? How can I tell male from female and from what age can I do this?
 
                                                                                       Al

 

[NickAu]

 
How old do babies have to be before they start breeding?

About 3 or 4 months old.

 

[Akasha72]

to sex guppies you need to look to the anal fin. The female's anal fin is fan shaped where as the male's is thin and slightly pointed. 
 
If the female is in with her young she will eat them if she gets hungry - just so you are aware.
 
Female livebearers can hold sperm for up to 6 months so even if you seperate her now from the boys she will almost definitely give you more babies over the next 6 months

 

[ImmortalRav]

I just had 19 new fry the other day.

 

[Essjay]

The fry will all look female at first. At puberty, the anal fin of the male fry will change into a gonopdium. If guppies are the same as endlers (which they should be as they are closely related) the first ray of the anal fin will start to elongate first, then the rest of the fin will shrink until it has become a gonopodium. If you can spot when the first ray starts to elongate, you can remove the male fry before they are able to impregnate their sisters.