Dwarf golden eel died randomly . Could kz flatworm stop be related?

[chopsuey84]

I keep an sps dominant reef with low nitrates and phosphates and my eel (i've had it for over 1 year) went missing for about 2 week and today i pulled it out dead still fat and "healthy looking". The only change I've made to the tank is my addition of flatworm stop, coral booster, and coral vitalizer. Is the eel death coincidence or could've the flatworm stop caused it?

 

[ndrwater]

I have heard horror stories of people using Flatworm exit and having the toxins the flatworms emit kill whole systems.
Usually this is the case when there is a massive infestation

 

[lion king]

Certain species that I would include eels, can react badly to many of these supposed safe treatments.