Shrimp question

[BigSkyRich]

Funny thing happened on the way to taking a look at my tank after lights out - amazing the things you'll see that you don't when the lights are on. Anyway, I was really surprised to see just about all of my (what I believe to be) Peppermints all congregated on both of my powerheads. Nope, they weren't stuck there, right where the powerhead and glass meet. They appear to be picking at stuff (although I just cleaned them yesterday when I did a water change). I have never seen this behavior before. There are like 6 or 7 shrimp docing this at same time. Anyone else experience this?

 

[Timfish]

NO, but I've not kept large groups of peppermint shrimp. Maybe a group spawning? Or maybe the powerheads are slightly warmer? Not surprised they're picking at stuff, algae and detritus can resettle on glass in just a couple hours.