Why is my Amano Shrimp blue?

what they eat. Sometimes my amanos turn blue, sometimes transparent, sometimes yellow-brown ish.

I've seen that as well. To me they're a product of their environment and will change depending on what they eat - perhaps they also change to look similar to their surroundings like a defensive camouflage... what threw me off is that you said other of your shrimps aren't like that so maybe they'll begin changing like that I'm not sure.

I've leaned this may also be associated with stress due to shipping & new water parameters.

Some of my new blue amanos are are turning to the more traditional amber color.

If anyone know of a food that would promote that blue color that would be are for the long term, I'd feed that. The blue amanos look very nice under my LEDs.

it may be trying to blend in and hide behind the blue string.

IME, it is usually stress.

When my amano had a bad molt and took on a badly deformed and crippled form, she was gray and blue everyday until she molted back to form.

I was at my LFS about a month ago, and they had just received a shipment of 500 amanos that day. They were in a quarantine tank. They all looked like blue pearl shrimp. I had to ask if they were sick, and the manager said they always come in that color, and turn their normal brown to clear/ yellow in a couple days.

they also turn that color when eating cladophora algae.

I don't know if it is from stress or food for sure but I believe it is most likely from food. I used to have a few fish in with my Amanos and I often fed my fish Hikari Micro Wafers that indeed has color enhancing ingredients. Apparently, according to Hikari, Spirulina and Astaxanthin promote color intensity. My amano's would always get some of the wafers that would sink to the boottom. During this period my amano's would turn blue.

I no longer use this food because I no longer have fish. And my Amanos have lost the
Blue in them.