Re: Can plants cause K deficiency in fish?

>From: Kevin Conlin <kcconlin at cae_ca>
>Date: Wed, 09 Oct 1996 10:19:25 -0400

>Diffuse whitish bumps, typically on the back of the head but which
>many occur anywhere, are characteristic of Chilodonella.  Take a skin
>smear and examine it under a microscope at 50-100x.  Look for a large
>heart-shaped organism with longitudinal rows of cilia.  Since many
>protozoans are sensitive to salt, perhaps what's happening is that the
>chloride ion in the KCl is inhibiting its growth.  Malachite green
>kills this thing good and dead.  Don't wait to long to treat it,
>as it can destroy the gills of susceptible fish.

My guppy has completely recovered, and shows no trace anymore of the
whitish areas. Twelve cc of 1 molar KCl in 20 gallons is a very low dose,
and I do not think that it would work like the recommended salt treatment
where the fish is put in a solution that is close to seawater in strength.
Two or three times in the past I have cured the same symptoms in guppies
with small additions of KCl.  In those instances, also, the guppies were in
planted tanks that could have been deficient in potassium.  If I ever see
the symptoms again in guppies, I will try adding some sodium chloride to
see if the chloride was the important addition, rather than the potassium.
In the meantime, I am thinking that the fish may depend on potassium in
their water to maintain normal concentrations in their tissues and body
fluids.  If this is true, then the fish probably would take up the
potassium through their gills by active transport, and it is possible that
aquatic plants could lower the potassium concentration to a level where the
fish's uptake mechanism would be inadequate to maintain normal
concentrations. I am hypothesizing that when the fish is potassium
deficient the white areas are a result of infection of some organism that
is normally a commensal (harmless), and when the fish recovers its normal
potassium concentration, it is able to recover from the infection.  In
aquariums, the ratio of plant biomass to water volume is much higher than
in nearly all natural lakes, ponds, and rivers, and lower than normal
potassium concentrations could occur.

>From: Jimcapwet at aol_com
>Date: Wed, 9 Oct 1996 10:30:46 -0400

>Well I think that it would be what my fish need and my plants could use.  So
>where does one who is not of a lab world find 12ml. of a molar (yes it's two
>units of measure) of KCL. I like to give my fish and plants some TLC (at the
>most an OZ or Lb.) all the time.
>In now sunny Temple Terrace, FL, ((north) Tampa for the post office only),
>where we did see Tropical Strom Josephine,
You get all the luck in Florida!  Well, maybe this winter we will get a
snow storm, or an ice storm here in Mississippi.

I have seen an all KCl salt substitute sold in grocery stores.  It should
also be possible to order KCl from a school supply company, such as
Carolina Biological Supply.  I know that Carolina will sell to individuals,
because I have gotten some stuff from them using an individual account.
Perhaps other school supply companies, such as Fisher, will do this also.
Carolina can be accessed at:

You can also get potassium alone as a fertilizer at some gardening stores.
This, however, is mostly potassium oxide, rather than potassium chloride.
I vaguely recall that Neil Frank is using this as his source of potassium.
Am I right, Neil?  If so, how is it working?

Paul Krombholz                  Tougaloo College, Tougaloo, MS  39174
In cool, dry Mississippi