what are possible causes of death outside of the usual parameters?

lost most of my colony over the past 2 months (started 4 months ago), however i’ve checked my parameters loads and they’re all fine, bar GH on the higher end. even checked with a fish dude i know that’s crazy about shrimp and he said they’re all perfectly fine and i should have a thriving colony, so my question is, what are other ways shrimp can die off, specifically over time, that aren’t caused by the typical parameters like ph, nitrate, ammonia etc? specifically for neo’s