Amano behavior normal?

[Potterygal]

For 3 days my 6 Amanos have disappeared from their normal activity. I can see 3-4 of them clustered onto sponge filter in back corner of tank the past couple days. I did see one molted shell  yesterday in different area ( 10 gal) 

is this clustering: hiding simultaneously in normal realm? 
my water quality is 

>10 nitrates, 0 nitrite, 0 ammonia, 6.8 ph,

gh 150/ Kh 40. , never chlorine 

First time w Amanos- not sure what to expect. For the past month they have been all over the tank EVERY HOUR of every day. 
thank you

( there is a reflection aspect to the shrimp photo)

Edited August 10 by Potterygal
Add info

[mynameisnobody]

Any animal that molts will know when it’s about that time. They will find a cozy spot with not much traffic, a spot they can have their guard down. As they molt they stop eating, molt happens and they still remain hiding until their exoskeleton hardens up. If not, they’re an easy soft snack. After they harden up a bit, they go on about their day as usual. Hope this helps

[Potterygal]

Thank you! I guess they have not gotten the memo that there are no threats in this lil ecosystem ! 😂15 chili rasboras only!

just seems odd they are all molting at same time🤷‍♀️