it must be spawning time because last night i noticed the same thing with my cleaner shrimp. this morning i noticed an egg mass attached to the the tank wall. i assume that is the egg mass from the cleaner shrimp but can't tell.
i figured it'd just be food for the corals and such.
Chances of raising them is close to zero. I tried for several years and have only heard of a few success stories at the waikiki aquarium and a commercial breeder in Great Britain. You are welcome to try - Be the first on the block. First foods are the problem. I had one survive 41 days.
One place for info is the Breeder's registry. A couple of years ago there were several lengthy threads on the subject. Several articles appeared in FAMA and other publications. Some names to look for are Karen Britain at the Waikiki Aq, Joyce Wilkerson, FAMA articles, and a book I can't seem to find right now called "How to Train and Raise your Pepermint Shrimp" or something like that. It's a non technical book on rearing the easier Lysmata Wurdemani aka Pepermint Shrimp. Anyway its fun to read as well as informative.
I just noticed that DT's Phytoplankton has the ingredients that was mentioned 10 years ago as the most probable first foods. This would make it super easy to attempt raising these guys again. Algae cultures were the worst/hardest part of raising the shrimp. Good water and cleaning the bottom of the tank is all that's left...