Another differentiator is the second segment on the tail. On males it’s the same shape as the other segments. On mature females it’s much wider, like the illustration in the sidebar.
But if they’re still young you just might not be able to tell. IMO all juvenile shrimp basically all look male.
yankjenets 
Blue Looks like a male, females have a more round back like the red ones
To me they all look female.
Blue looks male, red looks female.
For future reference: [This is the guide I use to sex shrimp.](https://www.shrimpscience.com/images/infographics/dwarf_shimp_sexing_infographic.png) You’ll be able to tell better than we can from photos.
Another differentiator is the second segment on the tail. On males it’s the same shape as the other segments. On mature females it’s much wider, like the illustration in the sidebar.
But if they’re still young you just might not be able to tell. IMO all juvenile shrimp basically all look male.
All of the Reds are female for sure.
I have my doubts about the blues … They look mostly like males to me.