October 18, 2005

Today's Pond Q&A

Today's Pond Q&A

In this issue:




Hello Carolyn,

You were so helpful before, I beg your indulgence to permit one
more question. About 10 days ago, I noticed my yellow koi has a
dark, rice shaped/size speck on its side below the dorsal fin.
There's also a tiny pin dot in the same color on top of his head,
but nothing else looks out of the ordinary. The specks have not
moved in all this time nor increased in size or number. I can't
get close enough to the koi to catch or look at it with a
magnifying glass. The fish all swim about and eat like pigs, as

Since several gold fish have changed colors over the years, I'm
not sure if this is a pigment thing, although at times it looks
like the "rice" has legs, but never worm tendrils. Fearing an
infestation of something, I did some web research and then
purchased Dimlin when we couldn't find Anchors Away for leaches
or anchor worms.

The pond has a biological filter, a UV light, water lilies and
other plants for filtration. Since we also have at least 2 frogs
in residence and birds use the waterfall pools for bathing, there
could be pests in the pond.

If we treat the pond (no goldfish have this problem) with the
Dimlin in my 6.3 ph water, will it harm the fish if it's NOT a
leach or anchor worm on my one koi?

Thank You

- Sue

Pond Filters, Pumps, UV's and More...
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Hi, Sue,

I am quoting from Doc Johnson's book, Koi Health and Disease:
beginner to advanced life-saving technology" on the topic of
treating with Dimilin for Argulus and Lernea (fish lice)-
"Some references suggest that the Argulus organisms can actually
inject a toxic or inflammatory compound into Ulcer sites that
also causes Ulcers." He goes on to say that this is not a
serious problem in ponds where Dimilin has been used.

"Dimilin", according to Dr. Erik Johnson, DVM, "is a gyrase
insecticide, that inhibits the formation of the crustacean
(Argulus) skin. When the Argulus tries to mature, it simply dies
out. That is why the Dimilin is so much more effective against
immature forms of the parasite than against the mature forms.
Even still, the Argulus adults are cleared within 3-4 days under
normal conditiions anyway."

However, even more important to your question is that "Argulus is
potentially devastating, but in reality, usually only a temporaty
scare, and a dose of Dimilin away from being a memory." Yes,
Dimilin is the treatment of choice for fish lice, whether Lernea
or Argulus, and if you see it on one fish, you have it on many
that you do not see. It is the one parasite visible to the naked
eye and surprisingly overlooked quite often since the fish
continue to "act normal". Signs of infestation would be
flashing, appearance of secondary ulcers or bacterial infections.
Fish lice are sucking crustacean parasites that will attack and
proliferate in your pond no matter what condition your koi are
in. Immunity has no effect on them. Argulus lays about 500 eggs
on the surface of rocks, or even on amphibians, such as frogs.
Eggs hatch in 4 weeks. In exchange for a blood meal, they inject
bacteria, toxic substances, fungi and other undesirable
substances in the feeding process.

Are you willing, knowing what you now know, to take that chance?

- Carolyn



Hi Carolyn,

I enjoy receiving the question and answer emails. They are so

I am a new pond owner and have some concerns regarding the
filter. The landscaper that installed my pond told me that he
installed a crate like filter filled with lava rock. When I
asked him how to clean it he told me it wasn't necessary.
Is this the case?

Also I have floating plants (lettuce) and it seems that a dirt
like substance attaches to their roots.

When I pull them out of the water, the water around the roots is
brown. The rest of the pond is clear, can see the bottom. Any

- Gail Cushman
Rochester, NY



Hi, Gail,

Are there rocks on the bottom of the pond also? I suspect the
landscaper was not given the right information. The system you
have should be cleaned thoroughly once a year. Most people do it
in the spring by taking out their fish and power washing the
whole thing. It's a big job. Maybe the landscaper is planning
on doing it for you?

If it's an Aquascape pond, then he's knowledgeable about the
maintenance of one. There is no such thing as a filter that needs
no cleaning, period. Those plants will die off soon, as they are

Don't worry about the dirt on their roots. They are filtering the
water also. And the fish should be eating those roots at some point.
Maybe next year. We call it "silt:" and it attaches to everything
unless there is enough of a strong waterflow to keep washing it to the

- Carolyn

Happy Pondkeeping!

MacArthur Water Gardens

MacArthur Water Gardens
PO Box 3628
Alpharetta, GA 30023-3628

Posted by bfogle at October 18, 2005 06:33 PM