In Chap. 8 we detailed the clear evidence that cleaner wrasse perform mirror self-recognition (MSR), via C-testing, rapidly after first seeing their reflection. But what processes occur during the average 30-min of C-testing before they recognize their mirror image as themselves? The exact details remain unknown, so to shed light on this, we conducted further experiments on MSR in cleaner wrasse. Surprisingly, we found that while they performed C-testing behavior, they were testing the hypothesis that the mirror image is themselves.