What are your collective thoughts on prophylactic cipro treatment on h. magnifica and/or m. Doreensis? I've had one riterri and a few LTAs decline and die on me 2-3 weeks after purchase with all my water params looking good, adequate lighting and flow, to where the only explanation I can think of is unidentified disease or questionable collection practices. I've got a healthy looking ritteri in QT right now, under observation debating whether or not to proactively treat with cipro or hold off as long as it doesn't start declining.
Just to be clear, Ritteri and mag are the same, magnifica being the scientific and more appropriate ID.
Most of us do not treat unless we see obvious signs of needing it, primarily deflation of tentacles, but QT and observation should always be done.
There could be a number of reasons why your other nems declined, even just a newish tank(less than 6 mo) could be an issue, normally not stable enough quite yet, high nitrates can be an issue as well, hard to say not knowing all about your tank and setup.