Age you can tell the gender and species of P Clarkii/ P Alleni?

Hello! New to the forum, new to this in general.

At what age/size can you decipher the gender and species of blue and white crayfish?

I have two crayfish, the blue one I've had for about a month and I believe is clarkii, but the white one I got a few days ago I am unsure if it's allenI or clarkii. Got them from petco, they had no way of telling me species. Looking at their shells how the plates come together, the blue one looks like clarkii. Can't tell yet on the white one. Sometimes it looks like allenI in some lighting, others it looks like the plates are almost touching.

Based on researching these two species for far too long on the internet, I'm pretty sure the blue one is a female. The white one I think is a male - but it's hard to tell with it being so small and translucent.

I've had the blue one for a month-ish, the white one is a new addition. I had a 10 gal tank which wasn't so safe anymore so I put the blue into a 2.5gal tank for the time being, and the white one is in a little tub. I've got a 20 gal tank that I just got from a friend over the weekend, so we set that up and it's cycling and doing it's thing as we speak.I'm getting ready to rehome the two - hoping I've got enough hide-a-ways (5) and obstacles to keep themselves entertained. I am really hoping the bigger blue one doesn't shred the white one to pieces - size, species differences, etc.

Any opinions, tips, words of wisdom are appreciated!

 

Welcome to the forum, I can tell you the blue is definitely male P. alleni. Could you get closer underneath pics and a frontal pic for the white one.

 

HI there!

The only photo of the blue I have is the very first photo. All of the rest of the underbellies are the white one. That being said, still a male? Other photos that the white one would let me take at a clear enough resolution. Will try tomorrow for more.

 

From what I can see, which is limited, I see Blue = P. allenI male and White = P. ClarkI male.

This is a crude drawing of what you are looking for. Under the eyes of the blue one you will see two dots, that is a P. allenI telltale trait.

 

Hi!

Thank you for the information about the dots under the eyes, you are referring to the false eyes by it's mouth? I only knew of the bumpy claw traits, and how the back shell/plates meet. Photo reference I've been using is

Also, based on your drawings and the internet, I do believe the blue one is a female- finally got a good picture on my lunch break today. There's no "hockey sticks" like on the white cray.


Underside of my blue cray



More of white cray - will try for more clear photos tonight.





Thank you for all of your help!!

 

Hi!

Thank you for the information about the dots under the eyes, you are referring to the false eyes by it's mouth? I only knew of the bumpy claw traits, and how the back shell/plates meet. Photo reference I've been using is

Also, based on your drawings and the internet, I do believe the blue one is a female- finally got a good picture on my lunch break today. There's no "hockey sticks" like on the white cray.


Underside of my blue cray
View attachment 203732

More of white cray - will try for more clear photos tonight.
View attachment 203735View attachment 203734View attachment 203733

Thank you for all of your help!!

You're welcome and I think you are right, it looks like blue is female allenI and white is male clarki.

 

Thank you! I can't wait until the white one gets a little bigger, so I can see more detail!
A few more questions if you don't mind,

If it's true that the allenI are more aggressive (she's a feisty one for sure!) , and due to the size difference in these two, do you think it will be immediate doom for the white one? I still have them in small separate housing. Have not introduced the two formally yet.

So if they are different species they cannot reproduce? Is it possible either could get aggressive towards the other afterwards, even without being able to procreate?


Thanks!!