Hi all I am fairly new to the hobby I have four swordtails and one which I thought was male now looks bloated as if maybe it's a she and pregnant, the gonopodium does have a slight point to it but b by no means as noticeable as my other definate male, their tail is also forked and not fanned out like other pictures of females that I have seen,I am aware that a pregnant female will have a black gravit spot under their anal fin, which I don't believe I can see but is this something that will develop f pregnant? Cheers dave

There is a lot of rubbish going around when it comes to sexing swordtails because they are unique when it comes to gender.

Late developing fish which appear to be female but which can turn out to be male, old females which develop a sword and what appears to be a gonopodium and so appear to be male along with a females ability to store sperm and give birth to several broods from a single mating lead people to believe that the fish is capable of changing sex. This is not the case, a functioning female (one which has given birth)cannot change in to a functioning male and a functioning male i.e one which has fathered offspring cannot become a functioning female. Sexing these fish is therefore a little hit and miss to be honest.
Gravid spots aren't always very obvious either, in some fish they are very dark and in others almost invisible. If the fish is very fat there is a reasonable chance that it is pregnant especially if it is in a mixed sex tank.

Hi there and welcome to FK

We have a good article here written my member Alysonpeaches that you may find helpful

Link here:
http://www.fishkeeping.co.uk/articles ... _molly_platy_pregnant.htm

In males you are looking for a Gonopodium which the ladies don't have. Just type in 'sexing swordtails' into google images and there are lots of good pictures.

The reason that females appear to have a gonopodium is explained in this thread.

http://www.fishforums.net/index.php?/ ... -swordtail-is-now-a-male/

These things are easy to research!

Thank you for the link. I was aware of this but it may be helpful for the OP.

I think anyone here would agree that sexing youngsters can be very tricky sometimes (I've always had problems with rams for example!) Perhaps my post should have read sexing 'mature' swordtails to avoid any ambiguity for the OP.

Far, far, easier with DNR for example where the males present with red fins early on, whereas the girls are yellow.