Re:Can plants cause K deficiency in fish?

Sometimes my guppies get what appears to be fungus or bacterial patches on
them.  These are rather diffuse whitish bumps that appear to come to a
head, somewhat like a pimple. They are definitely not Ick.   I have found
that adding small amounts of KCl to the water makes them go away in three
or four days.  Most recently, I had a 20 gallon tank with some zebra danios
and a female guppy that had been getting only room light for several
months.  I put some plants in it and a light on top, and the plants grew
quite rapidly, using the nutrients that had built up during the months of
low light.  Last Friday I noticed fungus patches on the guppy, and on
Sunday, I added 12 ml. of 1 molar KCl to the tank.   Today (Tuesday) the
guppy looks better, and the patches have become fainter.  This is the third
time I have cured guppies of this condition by adding KCl.  My guess is
that when I put in the plants (Ceratophyllum and Hygrophila polysperma)
they soon exhausted the K supply in the tank, and caused the guppy to
develop the symptoms.

Has anyone else seen this condition or heard about it?

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174
In Mississippi where we got missed by Josephine. Rats!