breeding swordtails

Question
Hello,
I have a pair of swordtails in a 10 gal tank that recently began breeding regularly.  I am not doing anything in particular to save the fry but there are hiding places so some are surviving.  I have noticed that so far all surviving fry are females..is there a reason for this? Do they start out looking female then change at some point?

Thanks!

Answer
how old are they?
usually they look female and then as they get older they look male, and then you know...depending on the fish breed, but can be as long as 6 months...

sometime though, males are known to eat males to stop the competition over the female, but thats very unlikely, there not choosy on what ones they eat