Baby Livebearers

Question
I have some little guppy babies that are just over two weeks old. How old do you think they will be when I can determine their sex?  I thought I may be able to see from their fins by now but they all look the same!! Also, when do you think I will be safe to let them into my big tank.  I have guppies and platies in it and one loach. Many thanks :-)

Answer
You should be able to sex them between 4-6 weeks.  The females will show a gravid spot (dark spot) just above  anal fin. You can put them in the bigger tank when they are big enough to not fit in the biggest fish's mouth!!  If you are not sure, take one, put it in the tank and see if anyone bothers with it.  It usually will happen quickly if someone is interested and I just swoosh them away with the net if it does.  It's something that you just get used to doing.

I hope this helps!  Get back to me if I can help you any further.  ;o)