So my tank crashed last year and slowly, all my fish started dying. The coral have all survived. I started ProziPro treatment at the beginning of this year (around January), twice and tried to add a fish again and it died. I got frustrated and neglected the tank. Some of the coral died due to my neglect, like some Acros and some Euphyllia, but, for the most part, all my coral are thriving and keep growing. I’ve since gotten back into the groove and bought new coral. They all seem to be good. I tested the parameters and everything seems to fine. So I decided to test with fish again. The clowns, unfortunately, didn’t last 24 hours. The only live things that are still in the tank are 5 hermit crabs and 1 snail. They’ve stayed alive for six months when no other moving animal (besides copepods, anthropods and bristleworms which have all taken over because the six line wrasse died almost a year ago). I don’t get it. What bacteria could be in the system that would kill a fish so quickly yet the coral and other invertebrates are fine? It’s been over 6 months without any fish. I’m truly at a loss here. I’m thinking about doing a 100% water change but I’m not sure if that will help at all.