Sunday, October 4, 2009

The Last Supper

By all accounts it was a good summer in these parts. And though summer is in its death throes, the end is coming less like a train wreck and more like a gentle, painless transition, the kind of autumn that makes for comfortable stories.
Somewhere along the way, the Koi go into an inactive, dormant state. The fish’s metabolism is greatly affected by water temperature. With no stomach (and no stomach acid) as the water temperature drops their ability to digest eventually shuts down. In the depth of winter, in their dormant state, there is little risk that the lack of digestive ability will cause problems, they have no appetite and they don’t eat. They can go months without food in this state.
But in this transitional stage, before the water temperature drops below 50 degrees the risk is great. The success (or failure) scenario goes something like this: Once the water temp drops below 50 degrees or so, the fish generally lose the ability to digest food, and the rule of thumb is no food at or below 50 degrees. Food in the gut at these temperatures is a death sentence. It tends to sit there and ferment (rot), septicemia sets in and the fish will usually die within a few days, a week at the most.
It takes about three days for the gut to empty, so if you are thinking of feeding on Wednesday, you need to know what the water temperature is, but you also need to know what the water temp will be on Saturday. I’m pretty tuned in to the crystal ball gazings of my friends at the National Weather Service out of concerns for riding my bike in comfort. This time of year I am also thinking about the fish.

The problem is, at temperatures in the low fifties the fish still have an appetite, they’ll eat and they can digest, but if the temperature drops, then trouble rushes in.

The water temperature has been gradually dropping in the last few weeks and for the last few days has been hovering between 52 and 56 degrees. I’ve cut back the feeding to every three days and not much food. I have been alternating between a low protein wheat germ based product (more easily digested) and a sinking medicated feed. Best to put them to bed for the winter with some antibiotic in the system as the fish go dormant a little before some of the parasites and bacteria that cause trouble.

Yesterday I spent much of the day, cleaning up in and around the pond. I removed most of the floating plants, trimmed and cleaned up the perennials and made a 50% water change.

I added a water conditioner (dechlorinator) and some enzymes to support fish health and beneficial bacteria, also a few chunks of plaster of Paris to increase hardness and alkalinity, it also helps clarify the water. I also added salt to bring the salinity up to 1ppt, and a product to control algae, a periodic addition. This is a lot of messing with the soup and with this much manipulation of the water chemistry, I needed to run the pump overnight to assure that everything was properly mixed and that the water was saturated with oxygen.

Unfortunately, last night there was a full moon in a clear cloudless sky here at Rocky Acres. The net effect was that the water temperature fell from about 52 degrees to 48 when I got up.

The fish are spending their time on the pond floor or in their ‘club house’.

I sank a piece of 8” PVC culvert in the pond figuring if they needed some place to hide from predators this might work. They seem to find it suitable and I really like the juxtaposition of the industrial wastewater outfall chic with the zen koi ambiance. Irony as art.

The air temp got up into the high 60's today so running the pump was essentially warming the water. The water temp came back up to just over 50 degrees. From here on out the pump will be turned off when the sun goes down and then back on in the morning.
A discovery!
As I was cleaning the pond on Saturday I discovered some little teeny spotty fish. They were Comet babies! We have a half dozen Sarassa Comets in the pond (fancy name for gold fish) and well, they must have been messing around without using protection because I found three little bablies. It will be interesting to see if they make it through the winter.

Anyway, it’s bread and water (sans bread) for the fish until April. I’m hoping for a mild and dry winter. Another flood would just not do.


  1. Dr C,

    So that's the problem with the temperature hovering around's a bit crisp but not crisp enough. ;-)


    Hey, are you coming to the road cleanup/meeting?

    Joe P

  2. Road cleanup? I don't think so, I seem to have missplaced my clipboard ... but I and Mrs C are planning to attend the meeting.

  3. So that explains why our goldfish in our backyard, plastic-lined, six foot diameter pond used to clump up in the bottom when I was a kid.

    It was my older brother's project. We had petstore turtles and tadpoles/frogs too, and we all loved to swat flies and feed the turtles. My grandfather especially would sit on a big log and swat flies and feed the turtle and goldfish for hours.

    Wonder what he was thinking all that time? He was like pond statuary. Or maybe a rumpled heron, waiting?

    Thanks for the pond-erous reminder!