All of my shrimps swim when my female amano molts, tigers, neos, babaultis, other amanos. None have every mated with her though. And seeing as how they have to connect belly to belly I have a real hard time seeing an amano not being able to just take one of her legs and scrape a neo off due to the size difference. And that's what you saw when you say 'mated' right? Belly to belly contact? Cause I've had juveniles attempt to mate many shrimp by landing on their back and hanging on and digging in, for lack of a better phrase. Sadly they didn't get the memo that ain't how mating works.