Totally agree with the bonsai story but sometimes you cannot control certain causes
I recently
Lost 80% of my stock
In a fowlr tank
All Parameters were spot on and there was nothing out of the ordinary
Recently found Out that a tree
Near my sump had gotten a bacterial infection and probably dropped leaves into my sump box and infected my water
Lost fish
3 yellow tangs
1 regal tang
4 black bar chromis
4 clown fish
2 anthias
2 butterflyfish
All within 2 days
A very sad day and really punished the $