I don't think I would chance it. Even if the rosy barbs can't actually eat the C. pygmaeus, they would likely terrify the tiny shy catfish. You might never see them. Mine are even afraid of Endler's livebearers.

 

I agree with Michael. The barbs are just a bit too nippy and the cories just a bit too shy. You might be able to pull it off with a school of the smaller, far less aggressive cherry barbs, though.

 

Well, after some thought I won't be getting any barbs I like the idea of a large school of White Cloud Minnows along with schools of both Pygmy Cory and Oto Cats. As you can see from my signature I have a few of these and want to incorporate them into the 50 gal. The 20 gal will be going away.

Thank you both for confirming my fears on the Rosy Barbs

 

The rosy barbs may very well start eating plants anyway.

 

Although you don't go for this combination and I agree that they probably will be scared at the beginning, I don't expect the barbs to do anything and if they try they will learn the hard way because their dorsal spine is a little venomous. So they're not likely to do it again and I expect them to show more and more once the barbs leave them alone. Still, perhaps not the best combination.

 

Thank you all for your input and helping me make my decision not to get the Rosy Barb I now have (21) White Cloud Minnows and will be ordering (10) each the Oto Catfish and Pygmy Corydoras very soon.