I dont think one of them has been doing any shimmiing. Ill watch them though. I love those little cories. They are most always moving around trying to find some leftovers. A question. I believe I have a female and 2 males. From what I have heard females are normally bigger in size and have thicker bodies. My 2 that I think are males are more slender and they have smaller heads. They both stick around the bigger one(possibly female) all of the time.