It's an antiprotozoal drug...so why is it in "fish tank cleaner?"The article did not mention the product name but a search of the ingredient cited in the article lists Ich treatment and algae control.
When I think of fish tank cleaner I think about an algae scrubber and my arms and changing water. You don't clean aquariums in the same manner as toilet bowls. It's mechanical not chemical.
The closest possible product are those sludge removers which are probably fairly harmless bacteria. Still no chemicals.
The media makes it sound like "fish tank cleaner" is like brake rotor, drain, or toilet cleaner.