Depending on which rili shrimp as there are red, blue, orange, and carbon. If your breeding RCS x Rili. Best to use a Red Rili as the Red Rili came from the RCS which will give you a mix of RCS or Red Rilli but eventually after several generations. You'll lose the rili pattern.
Just letting you know blue velvets are the product of red rilis being breed over generations. As for the blue body red rili. Those are hard to come by and dont breed true as they happen in red rili generations.
I miss the blue-body red rili. I remember when they were on the way out because blue velvets were so popular and everyone considered the BBRR to be super low-grade culls.
They bred fairly true and I had a small group of them at one point.