Bizarre one, I’ve amano shrimp in my tank and woke as much as this little man. Ive seen that its virtually inconceivable for them…
It’ll probably survive because it’s either a neocardinia hitch hiker or was already a juvenile when it showed up. Amano’s don’t hatch into little shrimplets like bee shrimp or cherry shrimp they have a larval stage that requires salt water. Once they look like little shrimp they are ready to move back to freshwater.
I agree with the other comment. this was a hitchhiker, could be from when you got the other shrimp or when getting plants. I’ve gotten tiny baby shrimplets in bags with other shrimp too.
Is it possible the shrimp you have aren’t Amanos? Shady or ignorant vendors will frequently mislabel things.