What do think happened?

Various possibilities:

1. Osmotic shock from the water change
2. Much more chlorine/chloramine in the tap water than usual
3. Osmotic shock from fertilizing plants
4. Gas emboli from heating cold water up in the tank
5. Other...
 
About a week ago I started noticing an ammonia spike in my newts tank. I couldn't figure it out, and 50% water changes did no good. I retested my tap water and found it now has 2ppm ammonia! When I started out in February it read as zero! I have to think, like Squint suggested, they've changed something in the water supply. Maybe it has something to do with the drought problems.
 
cbster said:
I didn't think about something being in the water but why would the other fish be just fine? I have a ph controller so the ph doesn't change.

Some fish are just more sensitive to various conditions. The Discuss are certainly the quickest to react to change. Any chance your co2 injection system had a spike and then normalized while you were not looking?
 
You have to think hard and ask yourself ,was there anything that you did or add, that you don't normally do. Eg changing brands of ferts , putting something in that you don't normaly do, that can include cleaning tools . There is the possibility that your water company may have added something different to the water ,but that is a very slim possibility. The other thing to consider is ,was an insectercide used near the tank by you or someone else(flyspray). It could possibly be a poisoning or contamenation of the water.
 
I'm thinking gas emboli as someone has already mentioned. Its summer and the tanks are warmer than usual (unless you have climate control, via a/c). Change water cooler than normal can cause a fizzing effect that looks like pearling. It causes air bubbles to enter the bloodstream and can cause heart failure and stroke.
Or a toxin, but not all fish being affected, my guess is, gas emboli.
 
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