911 All My Fish Are Dying!!!!

I wish I could help, but I don't know what this could be, other than if there were significant differences between the old tank and the new in water temperature, and/or Total Dissolved Solids, and/or nitrate since you state the nitrate in the new tank is 0, possibly they were in water with, and had been accustomed to, much greater levels of nitrate and other compounds that are in an old tank.

Like having fish in a old tank that has "old tank syndrome" and then doing huge water changes that subject them to too drastic a change.

How did the new tank water compare, regarding the parameters? I don't know what the remedy is for this situation if that is what is going on.

I don't think you need meds. I once lost my male leleupi and two tret cichlids from changing their tank, and the others were starting to act funny. I hadn't moved them to a new tank, but I had the bright idea to go from gravel to sand and change out all the decor. I took out everything - added sand, new piece of wood as a centerpiece and a bunch of new lace rock. My water was fine, and everything I added was fish-safe and clean. I immediately removed my fish and put them in another tang tank I had running to save the rest of them. I think your issue is changing too much at once. Tangs are very sensitive to water chemistry changes - although your water may be "fine" it was just too rapid of a change for them to be able to handle. I ended up putting other "test fish" in the tank for a little while, and eventually readded my tangs back to the tank SLOWLY adapting them, and have never had any issues. In the future, I will take an hour or more adapting them to a new tank by slowly adding the new water. I had saved half of their existing water and added that back, along with 50% new water from my tap (well water) that I always use for water changes. Since it was the same temp, I just dropped them in too quickly not accounting for the chemistry changes the new decor would add. Hope this helps you. Sorry for the losses.

How did you acclimate these fish to the new tank?

I am wondering if there was not some sort of chemical in the tank. Was it ever cleaned with a cleaner or bleach? It's possible the tank got poisones in ways not detectable with the Ni, NA and Am..


So sorry for your loss!

Sorry to hear that. It's impossible to say what happened without more information, but I agree that since they all died fairly quickly it may be a residual chemical in the new tank, like bleach or some cleaning product. Is the tank new or used? Did you test for chlorine, or use a dechlorinator? Is it cycled, how long, any other tankmates or survivors?

wow i am sooo sorry. It really sucks to lose a tank full of fish and have no idea why it's happening. Please keep us updated because i'm really curious as to what happened.

That totally stinks. Sorry for you loss