Swordtail Sexing

[Manty]

Hi folks,
 
Started Hobby on Jan 2nd when purchased a swordtail. When purchased was told sword was just developing gonopodium. Since then hasn't really developed but Swordtail has become fat similar to my female platys. So I assumed it was a female and that original suggestion was incorrect. Finally a week ago I was quite surprised when sword started to appear. 
 
Since original purchase I have also purchased a male (definitely) sword and he pursues my older sword relentlessly, constantly nudging stomach and in a similar way to the way my male platy pursues his female tank mates.
 
Any ideas folks? because I haven't got a clue!!
 
Thanks in anticipation

 

[BiggTexx]

Have you ran across this thread:  http/www.fishforums.net/index.php?/topic/363385-age-swordtails-can-be-reliably-sexed/
It may help out.

 

[DiddleBug]

Some livebearers can be slow to develop. Just give it some time and you'll know for sure! And sometimes males can get fat if they eat a lot.  

 

[Hairy_Trev]

Hi people!
 
I'm back again after computer issues and thought I would add my own comments to this topic....
 
I started setting up my tank in March, adding first fish about a month later and by June, I had 3 swordtails in there. (1 red/black male, 1 silver female and 1 orange female with white belly).
 
On July 27th, the orange female gave birth to 15-20 babies but partly due to my inexperience, carelessness and over-enthusiasm, many didn't survive. She did however, retain her dark gravid spot so I've been waiting since then for her to drop more...
 
The male was put with the silver female and she too gave birth to around 25-30 babies on 28th August (Co-incidentally, my own 50th birthday! Nice surprise!). All kept nicely protected in a breeding trap. After a few days, she was moved into a separate isolation area as she was fighting other fish, and the new fry were allowed the freedom of the full nursery tank (19 litres, lightly planted). These babies are doing very well, active and healthy, although I'm a bit sad that they have all developed varying styles of red/black colour and no sign of silver!
 
After about 2 months, the 6 survivors of the first group of babies have now got a new home with my brother. 3 had grown to about 25mm long, the others were smaller (around 15mm) which I'm told is natural. In a brood, some are smaller and weaker so they get predated on by other fish, allowing the larger siblings to escape and survive.
 
My brother has reported back that after 2 weeks, all are still fit and healthy and the larger 3 have settled in nicely to the main aquarium, while the smaller ones are kept isolated until they get bigger. He also says that 2 of the larger 3 are developing male characteristics at 2 months old! They seem to be sparring against each other, but also he thinks they are showing physical appearance differences too.
 
Is this likely? I'm told that the gonopodium will be the first indicator visible, at 3-4 months, and the tail only really develops after a year! I'm waiting to see what happens with the second batch, now 1 month old.
 
(NB: And just to reassure you... I am not planning on keeping 26 swords in a 19 litre tank!! This is just my nursery with no other occupants. When they are about an inch long, they will have new homes, some in my display tank, some in my brother's 100 litre + tank and some at my local fish store!)
 
Anyway... that's my own comment.... if any of my facts are wrong, please let me know as I'm learning from the start!!
 
Trev