Join Date: Jan 2013
Location: The Boonies, Arizona
Not sure about the Rosys, but I have 10 of the dwarf hovering zebra loaches (Yunnanilus cruciatus) in my 20L with a betta. They get along great, no nipping issues at all. When I first put them in, they were scared of D'Artagnan (the betta in question) and shoaled together tightly. Now that they're used to him, and because D'Artagnan is just a big puppy dog, they ignore him. They shoal pretty loosely, usually only about 4 at a time are together, and often they swim singly. They do need groups, and I would say in a 10g you could have 6. They are super cute and swim like little hummingbirds.
However, they are like pygmy corys in their behavior. You will see these loaches swimming mid-level much more than at the bottom. So, if it's bottom dwellers you want then I wouldn't recommend them.
"People have forgotten this truth," the fox said. "But you mustn't forget it. You become responsible forever for what you've tamed."
-Antoine de Saint-Exupery