I've been seeing a single CRS roaming around my tank since fixing my filter. Before I got the shrimp, I put a piece of foam into the intake of the filter. I just recently noticed that water was dripping out of the intake, rather than flowing out like it should. It took me so long to notice because I keep the outtake under water, and I don't do water changes as often since there's only 1 low bioload fish, and the only food I put in the tank is 1 cube of blood worms each week. Along with that the plants are basically nitrate sponges. I commonly get readings of 0 on the tank.
This shrimp has been pretty active, and Gary hasn't eaten him, so I don't think he's the problem. This entire time, the piece of foam I placed in the tank to prevent the shrimp from dying was the thing killing them.
I feel like more shrimp may be due if this one continues to do well.