Baby Swordtails! Sexing?

rynthae

Registered Member
Aug 21, 2009
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A few days ago, my girlfriend and I had quite a pleasant surprise. You see, that morning we went down to the local pet store and bought three swordtail fish (a male, a large female, and an adolescent small female) for our community tank. We acclimated our fish to the water and released them. After staying long enough to make sure they got along with our other fish, we left to get groceries. While we had been away, we turned off the light in the fishtank with the new swordtail fish in it. Upon coming home exhausted and heat-stricken, we gazed happily at the new fish.

All of a sudden, Kirstin exclaimed: "A baby!". I was really confused for a moment, but then I saw it. A miniscule baby fish that was all eyes and barely any body swimming around. Shocked at our discovery, and afraid the babies would be eaten by the parents, we took the bigger swordtails out and made a run down to the dollar store for a turkey baster. Luckily, we were able to save all five of the baby swordtails and separated them for now (until they get bigger). They're growing fast and they're really quick, too, and strong swimmers.

I was just wondering, about how long until they're big enough to determine their gender? I'm really curious to see how many males/females we get. :)
 
within a week or two you should be able to tell what sex they are
 
it'll definitely take longer than a week or two. i've had my swordtails for about a month now and they still aren't sexable. i'm thinking a couple more weeks maybe and i'll start seeing male fin growth.
 
i would have to say at least 2 months. i currently have about 25-30 green swords that are coming up from fry. out of all of them, only 1 started out early as a male. i have had 1 other change sex to male, dont think ive seen a male sword that big.

my first post, yay.
 
Up to a year. Swordtail sex determination is complex and some take a long time to show the characteristics, giving rise to the erroneous belief that they change sex.
 
It will be a few months if not more to sex swordtails. And even if you sex them right some males are actually females and turn into males later in life. I can sex my guppies in about a week but swordtails take longer.
 
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