make sure there is no copper in your fertilizer, shrimp are allergic to copper,also, with small tanks, its difficult to regulate the temperature when the lights go off. Make sure there is no more than a four degree temp change. The lights will sometimes raise the temp. really high during the day. Do you have a lid on your tank? Air fresheners, febreze, carpet powders and certain dusts can harm your fish. Make sure the bubbler is not vibrating the tank. How often are you doing water changes? How much water is changed and what is the flow rate on filling up the tank? Also, many ppl disagree w/me, but I use stalkings on my intake filter instead of a sponge, baby shrimp and baby snails can sometimes work their way through the sponge and into the filter. When you add sponge to the intake filter, it slows down the flow rate. I use a 30g filter on my 10g since the flow rate is so slow W/the sponge.