I have an established, very stable planted tank (120 gal). PH is controlled automatically @ 6.9, very low Nitrate, essentially o ppm Nitirite, Ammonia, Copper etc. Very high water quality. I have repeatedly attempted to add Amano and Cherry shrimp for alagae control with 100% death rate within 24 hrs. Here is what happens: 1) I carefully drip in shrimp for 2 hrs or so, 2) Add them gently to tank 3) Shrimp are active and immediately begin feeding on algae. 4) After several hours, shrimp stop moving and quickly die. I have exaustively eliminated any water quality issues. It appears that something they are feeding on is toxic. I do not appear to have any blue green algae (cyanobacteria). Shrimp are appear to be feeding on normal green algae on plants and glass walls. I'm totally baffled and a bit frustrated as I would really like to have some Amanos to help with algae. Any thoughts?