shrimp died

Hi, I have a 32.5g Fluval reef tank. It has been up and running for a little over a year. I ironically had a lot of success with inverts during the first 6-9 months of my reef tank. I had a serpent star, Cleaner Shrimp, and Peppermint Shrimp. I had to rehome the Serpent Star since it was too big...