October 19, 2005

Today's Pond Q&A

Today's Pond Q&A

In this issue:




Hi Carolyn,

Please can you advise me with regards to two things.

1. When do you stop feeding fish ponds or should you reduce
feeding gradually during the winter months.

2. I have about an 900 gallon pond and use a boiforce 9000 with
UV filter and an OASE15,000 pump.

All through the summer the water has been crystal clear and
could actually see the bottom which is 3ft deep in places but
now seems to be milky looking.there are about 40 goldfish and 5
koi of about 10inches in length and noticed that about 12 fish
seem to have huge blisters or ulcers on them.

On noticing this i have tried various medications in liquid form
but to no avail.

I have also changed 80% of the water but no change. One aquatic
center suggested i put some salt in but this has not helped but
it is since i have put the salt in that the water has gone
milky. All the water tests are all spot on except pH which is
9.0 but we do live in a hard water area. I have also have
several new born fish this summer and even four of these have got
these huge chuncks missing on there sides.

The pond was only put in march this year and now i seem to be
loosing interest because i cant quite resolve any of these

Please help I am getting seriously concerned now with my failings
and should I isolate the infected fish.

P.S. I live in south England, Great Britain and the winters are
fairly mild here.

- Andy

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Dear Andy-

That hurts!! Let me talk about the easy part first and get it
out of the way- feeding.

When the water temperature at night gets down to 55F you need to
cut out the high protein foods and up the vegetable protein,
like wheat germ which is a good staple food for spring/fall. As
the temperature drops, which it it may do (up and down for a
while before actually going down) nearer winter, and reaches
50F, stop feeding altogether.

Then, even if you have a couple of sunny days, do not start
feeding again until the late spring! That is very important. Many
people lose their fish because they forget that the food takes
4-days to go through the fish's digestive tract and out the
other end and any food left in there when the weather drops
again will putrefy and poison the fish. So in spring, this fish
turns belly up for no apparent reason, but we will know what
happened, won't we?

Okay, now, the epidemic you have on your hands- It certainly
isn't due to improper filtration. You have provided your pond
and fish with the best. What usually happens in a new pond is
"new pond syndrome" and the pond itself, in a year's time, will
become part of the filter too. It takes time to develop the
slime coat on the sides and bottom of the pond. That will
consist of beneficial and nitrifying bacteria, same as your

But I would recommend RIGHT NOW to isolate the affected fish.
Take them out and treat them separately, as it looks contagious.
I don't think blisters and ulcers are the same thing, but
whatever it is needs to be examined under a microscope for an
accurate diagnosis. More fish are killed by treating

The pH 9 is very dangerous and adding so much stress to the fish
now that they are unable to resist any infection whatsoever. They
should all be dead at that level pH. Most domestic fish can
withstand pH to 8.5, and even that is in the highest parameter.
The symbol pH stands for "power of hydrogen" in the water and
indicates whether it is acidic or basic. The ideal is in the 7.0
- 7.5 normal range. Yours is very high which makes ammonia
extremely toxic for the fish-- any ammonia. Adding salt to the
water was a good thing to do, but what amount did you add? The
proper amount should be .3% or 1# per 100 gallons, provided you
do not have plants in the pond. How does this happen? Although
there is no one way, by adding new fish without proper
quarantine, by buying from disreputable dealers, by adding
uncleaned plants, snails, frogs, turtles, or other visitors to
the pond, by water run-off after storms, poison from pesticide
spraying in your vicinity, and etcetera.

Knowledge is a good thing. Don't lose hope. Join a watergarden
or koi club and get some good help. One more thing, you have good
filtration, but only 900 gallons, so there are too many fish in
there. If we overload our ponds, nature will remove some for

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

- Carolyn



[In reference to a previous Q&A about worms in the filter]

Hi Carolyn,

Barb might be referring to worm-like leeches.

These are very contagious and harmful, and live off the fish
blood. They are in the same category as hook worms.

One author suggested soaking the fish in salt water (3%) for 10

I have experimented killing these with salt, on a small scale.
- 1% no effect
- 1.5 % after 8 hours :some died but the rest survived with
fresh water.
- 2% kill all in <8 hrs
- 3% Kill all in <10 mins

These leeches are parasite and came with the red blood worm that
I bought.

Happy killing

Best Regards

- hmWong



Hi, Gail,

However, at least from all the pond owners I have contacted,
which is many, our filter pads all contain leeches and nobody
knows from whence they come, but there they are. None have ever
been known to infiltrate the pond as yet and had they, the fish
would have eaten them, according to the koi club experts. Hook
worms which we call Lernaea cyprinecea are a different story
entirely and can be seen without a microscope, on the fish. And
yes, they are successfully treated in salt as you suggested or
Dimilin in the juvenile stage. Had Barb said there were worms on
her fish, the response would have been different, but leeches,
tubifex and bloodworms seem to be regular inhabitants in filter
matting and a normal part of the ecosystem.

- Carolyn

Happy Pondkeeping!

MacArthur Water Gardens

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

Posted by bfogle at October 19, 2005 06:35 PM