I have a 125g planted tank with (25)Amanos shrimps, (75) Cardinal tetras, (30) Rummy nose tetras and soon I will be adding (70) Red Cherry Shrimps. I was think of also adding some Harlequin Rasboras approx 30+. I have read and have been told that Harlequin Rasboras are peacful little fish and I'm sure they will eat baby shrimps but will they try to eat my adult shrimps? My other fish don't even give the amanos a second look.
My harlequins don't bother ghost shrimp that much. They don't seem to be interested in eating them, just seeing what they are. Rasboras are voracious little critters though...when it comes to feeding time, you can definitely see the relation to piranhas.
I, myself, have noticed that my Rummynoses are particularly attentive to me when I approach the tank and they think "Food!" IOW, hungry little buggers! With how much they are in the mid-bottom of the water column I'd be a lot more worried about them and the RCS.
No need to worry about Harlequins at all. They never touch my amanos or my cherries (when I had cherries). They usually stay to the top of the tank anyways so shrimp of all kinds in plants and on the ground will be safe.