Sunday last cleaned protein skimmer, changed 5 gals out of 58 gal tank, cleaned power heads. Everything nominal.
Came back six hours later and noticed skimmer had overflowed. Cleaned that up then noticed all fish dead!

Noticed whispy treads on few rocks. Checked chemistry - only ammonia and nitrate higher than normal.
I think I was cuke nuked!
Symptoms:
- Only fish died.
- Skimmer overflowed - released toxins reduce water surface tension causing overflow
- Filiments on rocks - these are cuke respiratory filiments expelled
Cuke nuke is most likely explanation. My dealer will take back the sea cucumber, but damage is done.
Does anyone know how long it takes for these toxins to disipate, or what actions are needed to remove them from the tank?