Anonymous
Force them on top of each other, put some crayfish porn on (national geographic best place to start) or use common sense and leave them in a small tank alone.
Grand Master BasserĀ®
Honestly, I THINK the one on the left is the female. That white "thing" on the underside of the tail looks like the mechanism that holds the mass of eggs. I could be wrong, of course. I see mud bugs more as food and live bait than pets, so yeah...
rbrgbarterr
The brightest color one is the male