Aggressive amano shrimp

Hi all, I have kept shrimp for years now and have just come across some very aggressive behaviour from my amanos. I recently added some lampeyes to the set up and it appears that one or two of the shrimp have been predating them. I've not seen this before, and did inquire with the shop before purchasing the fish if this was a possibility (due to their size) to which they said no.

I have today taken two biggest shrimp, females i think, back to the aquatics shop. They said they hadn't heard of this behaviour but i'm afraid it was true. I'm really hoping it was just the females that were showing this aggression. Has anyone else experienced this?

Shrimps will eat dead fish, did the lampeyes die first and were eaten later?

Are you absolutely certain they were amanos? Some sellers get shipments which also contain long arm (Macrobrachium) shrimps which are known to predate small fish, and they are sold as amanos, ghost shrimp etc. If the amanos in your tank had longer 'arms' that usual, they weren't amanos. We've seen cases on the forum where this has happened.

They are probably not amanos but a species that looks like them. I would return them immediately and try to get the real amano shrimp

Amano shrimp (peaceful) in the first pic, "whisker" shrimp in the second pic (aggressive)
Notice the long front appendages with pincers on the "whisker" shrimp

It was definitely amano, but very big.