How late do Xiphophorus alvarezi males develop?

[seba]

I have 8 Xiphophorus alvarezi juveniles that are about a year old and none of them have developed a gonopodium yet. I had a group of 1 male and 4 females that I unfortunately lost last year and these juveniles are all I have left. I know wild swordtails can take a while to sex out but how much longer should I wait before accepting there won't be any males? There's a couple more slender looking ones but almost all of them seem to have a gravid spot. Would be a shame to end up with just females as they are not easy to find around here.

 

[Colin_T]

Post pictures of them.

They should be sexually mature at 12 months and are usually mature at 6 months and if well grown can breed at 3 months. If they have been well fed, get regular water changes and aren't kept in really cold water, they should be sexually mature and if none of the fish have grown a gonodpodium they are probably all females.

I'm not sure if your species can but a lot of swordtails can change sex from female to male. This normally happens if there are no males present for a while. The biggest female will turn into a male and will breed with the remaining females.

@emeraldking might have more info on them.

 

[GaryE]

I only had alvarezi for 3 generations, so the sample size isn't huge. Like a lot of non hybridized, non commercial swordtail species, they mature later than pet shop swords. Mine always had a few early 3-4 month males, with the stronger healthier males developing by around 8 months at the latest.
Sometimes you get what you think is a gravid spot as it seems the pigment that lines the sword extends from along the lower belly. I saw that with helleri, but don't remember for alvarezi.
My Xiphophorus mayae were huge and a little over a year when they developed gonopdiums and swords.
I lost my alvarezi to an all female batch, and you may have too.

 

[emeraldking]

I still keep those Alvarezis. If there are actual males between them, they can show the male traits between 3 months and just over a year. A female that will change into a male, will keep the gravid spot but won't produce eggs anymore. And it doesn't have to be the largest female specimen that will change into a male. In female swordtails there's an autosomal locus with two alleles, A and a, which affects sex determination in XX fish. If the genotype is AA, the fish will be female (and will remain female during the whole lifecycle), and if aa, the XX individual will be male (so, yes...there are actually XX males next to XY). Aa genotypes are predominantly female (born with male and female gonads) but have the ability to change sex. And they'll be fully functional males.

 

[seba]

I only had alvarezi for 3 generations, so the sample size isn't huge. Like a lot of non hybridized, non commercial swordtail species, they mature later than pet shop swords. Mine always had a few early 3-4 month males, with the stronger healthier males developing by around 8 months at the latest.
Sometimes you get what you think is a gravid spot as it seems the pigment that lines the sword extends from along the lower belly. I saw that with helleri, but don't remember for alvarezi.
My Xiphophorus mayae were huge and a little over a year when they developed gonopdiums and swords.
I lost my alvarezi to an all female batch, and you may have too.

Thanks seems like I may be out of luck. I'll give them a couple more months before moving on from them and hopefully I get a late bloomer.