If you're talking about Boraras brigittae, they will absolutely destroy shrimplets. Same probably goes for similar fish like maculatus.
You have a very strange Boraras!
It so happens that I have about five dozen Boraras ( brigittae, micro and maculatus); more than three dozen Rasboras ( heteromorpha, h.black and rubescens);a dozen of glolight tetras; about three dozen of neons, inluding green ones; about dozen and a half of Celestial danios and Red tail Garras - all of them about three month together with RCS-es and the result of this mix is an excess of RCS-es in my 180, to the point, where all plants look like christmas trees with red on them.
I have to add that I have the back wall covered with Java Needle leaf, Windelow and yet anther,narrow leafed variety, as well as Java moss. It is the plant cover which protects shrimplets, and if one is to have RCS-es with any kind of fish, one has to provide a safea hatchery for them. I noticed that large growth of Pellia provides also excellent cover and a feeding ground for shrimplets.
I have noticed only very sporadic predation on small shrimplets by Black Rasboras. And I wish that some of my fish would start thinning out the RCS-es....