Aphids on Lily leaves

wrote:

LC means lethal concentration. So harm without killing them will occur at
lower doses.

And the often-discussed problem with using LC & LD levels in approving any
kind of chemical is that it assumes the only issue we're concerned with is
fatalities. There is likely no data available at all on long-term effects
of sub-lethal concentrations of the soap (though there are probably figures
for LC25, etc - and it would be worth knowing whether the lethal effects
drop off quickly or slowly from the 18ppm value).

If your fish recover completely from any damage due to a low concentration
of the soap (if there's no sign of gasping, they probably will - but those
would be your koi you're experimenting on!), then only the LC values really
matter, but if there's permanent damage, every time you use the soap things
will get worse. I can't help thinking there's a good reason for saying, on
the label, not to use it around aquatic animals.

"Snooze" wrote:

A few spritzes of the stuff is about one ounce? Or about 0.6ppm. At that
concentration it's not even worth bothering about.

fwiw, "...highly toxic to aquatic invertebrates. The LC50 was determined to
be 0.57 ppm in a 48-hour acute toxicity study with Daphnia magna". A neat
coincidence that you picked that number (I wouldn't have thought "a few
spritzes" was really as much as an ounce)

_My_ fish have always got most of their food from browsing for aquatic
inverts.
--
derek