Fish dying/dead - Heavy Breathing - Need Help

[mws]

Originally Posted by phreezee

Powerheads leaking voltage? Do you have a grounding probe?

This happened to me

It has nothing to do with voltage. Brand new powerheads are coated with the staff what is not toxic to the fish directly, but can reduce oxygen levels. And of course some fish is more sensible to low oxygen levels then others.

Same thing with sea hares. If harassed it may release a purple fluid into the water, which is not toxic, but may reduce oxygen levels and make some fish to suffocate.

If this is the case adding a air pump would probable help fish to recover.