our shrimp was small, depending on the size of the star, maybe once every 2-4 weeks. Always go for the bigger star. Same price, and last longer. You can try talking up a deal with your LFS to order them for you. Maybe do a bulk order and keep them in a sump. Watch the stars with corals though, as they will tear it all up. We had one that was doing fine for a while, but ended up eating a nice piece of orange encrusting monti.