Male P.menchacai sexual precocity

[mshuangchao]

Hi everyone, lately I've noticed my male menchacai's (barely 30cm) claspers have enlargened quite a bit and have started to uncurl. I thought they matured at a much bigger size, for this specimen has not even fully developed it's colors yet (not a very strong contrast between the yellow and black).
This concerns me and makes me worry about the prawns I feed them, could this be due to hormone residues in the prawns (probably "methyl testosterone" for it is sometimes illegally used to increase prawn production) ? Or am I thinking too much and tiger rays can natrually mature at such a small size?

 

[skynoch]

Mine probably started to uncurl at about 14" but are slow growing compared to my other males claspers. He's now about 18-20" and the black and yellow still are not that prominant but he just got put in with some females 2 weeks ago and has started to show some intrest in breeding with my flower. Is yours in with any females?

 

[amazongirl]

This question is a bit challenging to answer for me because we have based sexual maturity on whether or not we have seen pregnancy occur. Since we keep our tigers only with other tigers, the female tiger also needs to be mature and in the right conditions to breed (which seems to be tougher for this species than with many/most of the Potamotrygons) to know whether I have a mature male. I don't think you can base male sexual maturity entirely on clasper appearance.

That said, in my experience we had claspers thicken up on males at least 5 years before we had our first pregnancy with this species.

 

[FishDog]

This question is a bit challenging to answer for me because we have based sexual maturity on whether or not we have seen pregnancy occur. Since we keep our tigers only with other tigers, the female tiger also needs to be mature and in the right conditions to breed (which seems to be tougher for this species than with many/most of the Potamotrygons) to know whether I have a mature male. I don't think you can base male sexual maturity entirely on clasper appearance.

That said, in my experience we had claspers thicken up on males at least 5 years before we had our first pregnancy with this species.

Interesting and discouraging all at the same time.

 

[skynoch]

This question is a bit challenging to answer for me because we have based sexual maturity on whether or not we have seen pregnancy occur. Since we keep our tigers only with other tigers, the female tiger also needs to be mature and in the right conditions to breed (which seems to be tougher for this species than with many/most of the Potamotrygons) to know whether I have a mature male. I don't think you can base male sexual maturity entirely on clasper appearance.

That said, in my experience we had claspers thicken up on males at least 5 years before we had our first pregnancy with this species.

So would the thought be the the females take long to mature, the male, or both. Or do you think it might be just do to the right circumstances if you had to guess?
Where the males trying to breed with the females long before the pgregnacy happened? How long was the pregnancy?

 

[mshuangchao]

Mine probably started to uncurl at about 14" but are slow growing compared to my other males claspers. He's now about 18-20" and the black and yellow still are not that prominant but he just got put in with some females 2 weeks ago and has started to show some intrest in breeding with my flower. Is yours in with any females?

Yes, my male is with a female tiger ray who is just a bit bigger than he is.

 

[skynoch]

just curious because some people say they're males mature faster if they are with females.

 

[mshuangchao]

"That said, in my experience we had claspers thicken up on males at least 5 years before we had our first pregnancy with this species. "

5 years! Darn that's a long wait!

 

[amazongirl]

So would the thought be the the females take long to mature, the male, or both. Or do you think it might be just do to the right circumstances if you had to guess?
Where the males trying to breed with the females long before the pgregnacy happened? How long was the pregnancy?

I'd guess that they both take longer to mature than many fw rays, but that perhaps the females also need to be larger before being sexually mature. Our group consists of 2.3 and only the largest female has bred. I do think that this species is more finicky when it comes to breeding but I do not know why- something is missing is what my gut tells me.

Males were not trying to breed with the female before our initial pregnancy. We do see evidence of reproductive behavior now (bite marks and such) that often do not result in a pregnancy.

Length of gestation.... This to me is an interesting question. It seems to me that many hobbyists count pregnancy beginning as the time that they see a mating behavior or evidence that this has taken place but we see this with no pregnancies and I have had pregnancies where a female never looked chewed on so in my opinion this is not an effective way to judge length of pregnancy. Also keep in mind that elasmos are known to store sperm, delay implantation of fertilized ova and a whole bunch more interesting reproductive quirks that may occur in this family as well. So, we usually try to base pregnancy start on when we see a pup in utero using ultrasound. This doesn't necessarily mean that we couldn't have missed a pup on an earlier exam, they are tough to see when they are really young, especially with a female that will not sit still. We also have a more limited number of pregnancies we are basing our 'gestation guess' on with this species. That said, at this time my best guess from the data we've collected is ~ 20 weeks.

Hope that helps.

 

[mshuangchao]

Intresting info, thanks!
I also have a pair of antenna rays (Plesiotrygon iwamae), and I've heard they mature at a even larger size, don't even know if any one has bred them before!