(Ed. Note: the following is an extended conversation - Bill's words are in red, Bob's in green.)

Hi All. I saw your email address in the Midwest Koi and Pond Society web site.

We are definitely at the "low end" of the intensity of Water Gardens, but have a problem this year that is threatening our entire population of Koi and Goldfish. We have Furunculosis (Hole In Side) based upon my very limited knowledge of koi diseases, and due to observations off various pictures of diseases off the web.

Briefly, it must have been due to the difficulties in keeping our water quality... it has been a large battle all year. No new fish introductions this year whatsoever. I've had horrible problem with Alge (Green water), as well as Ph fluctuations. Amonia and Disolved Nitrites have not been a problem this year (For the most part).

I have been testing (Ph, Salt, Amonia , etc.) and attempting to make non-radical corrections all year. including ~ 75% water replacement if extreme levels were observed.

We have two outdoor "ponds" of roughly 125 gallons each.

We have been treating with "Tea Extract" bought from a local store, and running our salt content towards the "High Side" of recommended levels. This in some cases appears to be helping (appearing to reduce some of the ulcers", and most of the fish affected are extremely active in normal activity, however seem to have severely reduced appetites (floating food).

We have had fry this year in both tanks, with the larges fry now showing the disease. Our goldfish and koi (All about 6-10") are showing signs of the disease now, with at least 3 severe cases.

ANY SUGGESTIONS on treatment (specifically in this region of the country... temperature, etc.) would be appreciated.

Since we are small scale hobbyists, we are not interested in "Expensive" treatment, and would put down the entire stock if there are no hopes, however most of the fish have been with us for about 4 years, and hence the request at any thoughts to save them.

Thanks in advance for any ideas. Please drop me an email to both my work email and home if any of you have time to respond.

1) How many fish, and how many of them are Koi in each pond?

2) What is your filter setup? Do you have biofilters?

3) Do you have a UV plumbed in?

4) How much shade?

5) What's your Alkalinity?

Your ponds are quite small, and 125 gallons without a filter is barely enough for one koi. If you do not have protection from sunlight, your pond temps will be swinging widely from hour to hour, as will your pH and DO levels. At first guess, your main problem is mostly the Third Law. "There's Never Enough Water".

Bob Passovoy

At 11:49 AM 8/16/04, Bob Passovoy wrote:

> William,
> I'm going to ask you for more information about your pond. What you've given me is not sufficient to make a guess.
>
> 1) How many fish, and how many of them are Koi in eachpond?

Top Pond is 6, 1 is a Koi, rest are Comets. 1 comet is smaller ~ 4 inches. Others are at least 6", Koi maybe 10"... Bottom Pond Now has only 4 fish in it. 2 Koi, one ~ 4", other ~6" ... two other goldfish are about 6-8".

Moved the initially infected fish to bottom pond (Was Empty this year intially) when showing signs of infection. Now top tank fish have just started showing signs last week.

> 2) What is your filter setup? Do you have biofilters?

Both Ponds are Biofilters. Top filter is rates as a 3K per hour, using two sponge stages, and final stage are ceramics. I forget the name of the manufacture, but it a very popular type.

Bottom pond is two hard sponge stage (Fine and Coarse), with Plastic bio-media. Feeds a 800GPH Pump.

> 3) Do you have a UV plumbed in?

No. Usually take fish into a combined 100 Gal stock tank in basement, where have a 18W UV filter plumbed in. Could Easily accomodate a UV to plumb in, is that would be a significant improvement.

> 4) How much shade?

Top pond... None. Horrible Algae problem this year... No Lillys, just Stalk plants. Sun hits it starting 11am until about 4pm full sun over summer.

I have treated with Algeacide to maximum dose on bottle.

Bottom pond is much more shaded... maybe 1pm to 4pm in sun, no green-water problems this year, but get bad string algea during fall months.

> 5) What's your Alkalinity?
>
> Your ponds are quite small, and 125 gallons without a filter is barely enough for one koi. If you do not have protection from sunlight, your pond temps will be swinging widely from hour to hour, as will your pH and DO levels. At first guess, your main problem is mostly the Third Law. "There's Never Enough Water".

I was afraid that you were going to say that <GRIN>.

.PH Lower than 7 for sure.... haven't test in a few weeks, but want to say 5.5....

Past years, have attempted utilize "lilypads" as a source of sun protection. Could cover upper pond to reduce sun-exposure.

Is Furunculosis fishborne or waterborne (or unknown)? I could not seem to find an answer. Depending on transmissibility, I have a friend with a "NEW" (1 Full season) 1500+ Gal with plenty of room, but would never consider giving away stock if there is even a possibility of cross contamination.

HOkay. Not as bad as I'd feared.

You seem to be adequately biofiltered, but your koi are going to challenge your filters as they grow. Goldfish are much easier on the ecosystem, and do better in small ponds.

The floating "pea soup" algae will disappear if you stick a UV unit into the filter outlet. All you can do for the string ("hair") algae is limit sun exposure and plant lots of pond marginals and lilies. Algaecides do not work, and ultimately will poison your fish, your garden, and your pets.

Consider building a gazebo or trellis arrangement over your ponds and stretching shadecloth over the top. That will also lessen the temp shifts and ease the stress on the fish. Airborne predators will have more difficulty recognizing your pond as a "Migration MacDonald's", too. Encouraging grape vines, Clematis or climbing roses up the posts and sides of the trellising will make it really pretty.

I noticed that you did not answer my question about alkalinity. You need to go back to the website and read up, but briefly, alkalinity is a measure of the ability of your pond to maintain a stable pH. It measures the amount of carbonate salts in the water (80-180 is considered optimal), and these are responsible for sucking up the extra organic acids produced by your biofilters as they convert ammonia to nitrite to nitrate (to feed all that algae!). A small, filtered, closed system like yours will chew up your available carbonates quickly, and your pH will shift widely, often becoming acidic enough to damage your filter's beneficial bacteria and your fish. If you are not measuring alkalinity, You Should Be! Deficiencies in this essential component of water quality can be made up with Arm & Hammer Baking Soda (pure Sodium Bicarbonate!).

"Furunculosis" is a serious misnomer. The problem you describe , also called "Hole in the Side Disease", is an infection caused by a bacteria called Aeromonas aerogenes. It is almost always an opportunist, and indicates that something is stressing your fish beyond the ability of their immune systems and energy stores to defend against it. The most common stressors are rapid environmental changes (pH and temp shifts), injury, parasitic infestation and problems with osmotic balance.

I think your major problems are volume and temperature related, as well as sun exposure. The best thing would be to get your fish into a holding tank and dig them a big lovely, deep, shaded and filtered new home.

Bob