I'll assume we can rule out starvation and osmotic shock. They are very sensitive to toxins, any chance of that? Excess Iodine is what kills most of the ornamental shrimp early.After 9 months my fire shrimp, Stinky, just died. Went from perfectly healthy and following his normal routine to dead. Can't figure it. It definitely wasn't near the end of its life span of 2.5 years when I bought him.