VicB18

So I bought 1 Pb a few months ago and a few weeks later bought 2 more. Put them into a cycled tank which for some reason had a die off of guppies and one PB died. I put the survivors into my community tank and one seemed to do well. Have not seen the other since. Last weekend I put the healthy looking one into my shrimp tank and this morning it died.
Im at a loss. The tank it came out of and the one it went into have the same parameters, the latter probably the best of my tanks as its full of happy Cyclopods. The shrimp, Betta and syndodontis that live there are thriving, even crystal red shrimp. Any ideas? Do they just hate change?