im absolutely not being rude just responding to posted details about your tank. I realize you claim the cycle was completed, but many doubt that as well based on details of the original thread and there was no digestion test to show the ability to handle the bioloading from the fish. few would deny that adding fish to barren base rock that wasn't pre cycled isn't stressful. your tank may indeed be fully cycled and this wouldn't apply, but, from the details posted it cannot be left out. incomplete filtration base can def cause stress, and register as shrimp deaths etc just a point to consider.
There is no additive for what you are seeking. Currently we are unable to rule out that your bioload was introduced too soon, standard new tank shock. this is mentioned for no other reason other than cycling science details/impacts etc.
knowing when a cycle has ended, and fish bioloading begins with regards to uncycled rocks has a specific test to tell when its ready. without the digestion test, only guessing is possible, so it cant be ruled out. another thing that makes responding to untested variables really hard is sometimes animals simply die of natural causes but aquarists will always see it as a param issue, with the current info known about the tank its not possible to establish a cause, only rule them out.
