Two weeks ago I saw some beautiful adult Fire Red Cherry Shrimp at my favorite pet store, which all looked very healthy. I bought 5, and added them to my Cherry Shrimp Colony, which has been set up for 4 years, without quarantining them. I drip acclimated and they seemed to settle in nicely.

A week later, I found all the new ones dead and removed them. A couple days after that, I suddenly saw a few of my adult females dead. They seemed to have some white bands around their body and were a bit pale, and a minority were in two pieces. The shrimp were active and acting normal right up to when I find them dead. I haven't found many males or juveniles dead, mostly just adult females, some of which are Berried. None of the living shrimp are attempting to eat the dead bodies. When the deaths first started, all water quality was excellent. Within the next few days, I found more dead every day. Today, a week later, the death toll is at thirty. Today I checked the water and found that Ammonia and Nitrates have become elevated, probably from all the bodies. Ammonia was at 0.25 ppm, Nitrates at 30 ppm (extremely high for this tank, which usually has 0 to 10 ppm Nitrates). Nitrites were 0 ppm, Copper 0 ppm, pH 7.2, temperature 23 degrees (74 F). I did a water change with store bought water to lower the Ammonia and Nitrates, and intend to keep doing so daily if I see any bodies to try and lower their affect on the water quality.

The tank has had Cherry Shrimp in it for 4 years, no other tank mates. Size is 40 litres, it has a Marina Slim S10 filter with added biomaterial and a Jager heater. It's heavily planted with Micranthemum 'Monte Carlo', Downoi, and 4 types of moss attached to Cholla wood. Substrate is eco-complete. I feed the shrimp every other day with Hikari Shrimp Cuisine, Fluval Shrimp Granules, and Azoo Max Growth and also leave green algae on 3 of the 4 aquarium walls for them to eat between meals, plus the biofilm on the mosses. 15-25% water changes are done weekly.

I have no idea what's killing them. I'm assuming it's an illness, but I don't know what to look for to tell what it is or how to treat one if I do find out what the illness is. This is the first time I've ever had a problem in this shrimp tank. Any advice at all on what could be going on would be appreciated. I'm afraid of losing the entire colony at this rate.