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Water Changes, Winter & Hormones

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  • Water Changes, Winter & Hormones

    Some studies indicate that hormones can have an effect on the growth of Koi. This is oft cited as a benefit to weekly water changes of 10% or so. Aside from the obvious benefit of better quality water is anyone more familiar with this nebulous subject?

    Fo instance, as we are in the winter in my area, is there any benefit to continuing the normal summer regimen of water changes? Feeding has all but ceased, so the filter load is way down. Are these hormones also on the decrease? I realize that there are still things going into the biological soup from simple respiration. But, are these specific growth limiting hormones an issue in winter?

    Seasonal Felicitations!

    Jeff R. :lol: :shock:
  • #2



    I too have read this on many occasions, it was always said that koi would only grow to the size of their given environment. I think there are too many cases where this is proven to be incorrect.

    I think the actual volume of water is less of a problem than not actually providing a big enough support system, i.e. filter and aeration. I have no real evidence to back this up however, it's just my opinion/hpothesis.

    Mark Gardner


    • #3

      Hormones In Winter

      Great question and I have no answer. Have not seen anything on the topic in print. It seems sensible, however, that as koi metabolism slows the production of hormones/pheromones will also slow. As a result, I would think that water changes for the purpose of reducing the hormones would not be as important in winter in cold climate zones. However ....

      However, unless your stocking rate is very low, I'd consider 10% weekly water changes during growth periods to be much too small. I am a water change freak and would not suggest that everyone do as I do. (Minimum of 50% per week.) The recommendation of 10% per week comes from the aquarium hobby where recommended stocking rates are nothing compared to koi ponds, and that aquaria recommendation is a minimum 10%. Actually, it is typically a "minimum of 10% - 20%". If your goal is to maximize growth, then you should develop a regimen for frequent, large water changes, or partial flow through systems.

      At 10% per week water changes, assuming a constant rate of pollutants being introduced to the pond (nitrate, hormones, metabolites etc etc), you will have continuous build up of pollutants for approx. 30 weeks ... the equivalent of the entire growing season in cold climes. You will reach equilibrium at contamination levels ten times what is introduced during each week. At 25% per week, you reach equilibrium at a contamination level of 4 times the weekly input. In nature and mud ponds, the contamination level is virtually nil due to dilution and natural processes.

      So, if you are only doing 10% water changes, you might well want to continue during the winter in order to reduce the contaminant level in the pond so you are off to a good start when temps begin to rise. I can't think of anything positive about leaving fish in high level contamination for 3-4 months when their systems are weak and not being fed etc.


      • #4

        Thak You for the Input

        My pond is 2,880 US gallons including filters. During the heavy feeding months I backflush and change probably 10 - 15% of the water every two to three days. The fish were fed very heavily on HiSilk & Hikari Hi-Growth during the growing season. No problems with indications of poor water quality except for the occasional spike in Nitrite which was normally repaired within three days. The growth of the koi and the koi involved may be of interest. The following koi were introduced on May 28, 2003 and were measured again on November 1, 2003 during their fall checkup.

        Kohaku May 28 6" November 1 16"

        Kin Showa May 28 5" November 1 15 1/2"

        Sanke (Matsunoske) May 28 6" November 1 14 3/4"

        GinRin Ochiba May 28 6" November 1 15"

        Hi Showa May 28 7" November 1 13 1/2"

        Hi Utsuri May 28 7" November 1 15 1/4"

        Sanke acquired 7/3/03 17" November 1 20"

        Kujyaku acquired 7/3/03 15" November 1 18"

        Showa acquired 8/31/03 15" November 1 16 1/2"

        Additionally there was an algae problem in early June. This pond was new and so perhaps that was to be expected. Being a newby, I did not want to experiment with expensive Nissai & Sansai so I started with very small koi. I must say that I was gratified by the results considering that the design of my pond leaves much to be desired, i.e. - no bottom drains, Challenger #50 is main filter and etc. I added a Foam Fractionor in early October and have been satified with it's results.

        Admittedly the stocking levels were very low in the beginning and that probably has much to do with the growth results. The challenge will be to maintain water quality as they grow until funds can be had to re-build the pond. A challenge I suppose most Koi keepers face. This was what led to my original question of water changes and hormones. Perhaps there will always be more questions than answers, but I appreciate your sharing your views, opinions and empirical findings.


        Jeff R.


        • #5

          Mike M.

          Mike M.:

          "So, if you are only doing 10% water changes, you might well want to continue during the winter in order to reduce the contaminant level in the pond so you are off to a good start when temps begin to rise. I can't think of anything positive about leaving fish in high level contamination for 3-4 months when their systems are weak and not being fed etc."

          Sorry, I forgot to respond to this. I live in Dallas and our winter season is generally from December to January. I have backed off on the back flushes and water changes to about every ten days. As a result, the water quality may not be as bad as it first appeared. I certainly hope not! Let me know if I am missing something.


          Jeff R.


          • #6

            Dallas Water Changes

            Great growth rates I think .... about what can be gotten in central Florida!

            With two 15% water changes per week, I think most koikeepers would say you are doing it right. I'm in a warmer area than you, more like Texas' southern gulf coast, so I never stop water changes. Given the cooler temps in Dallas area, I can't say one way or the other. My bias is always in favor of more fresh water, particularly if you get a lot of leaves etc in the pond. Without bottom drains the water challenge is certainly greater ... I know all about those challenges.


            • #7

              I dont change water as such empty main vortex and flush the other 2 once a week twice in the summer works out at about 5% got a 600 gal q/tank in garage with 50 small koi growing on over winter do the same works out at 10% growth rates are good in both ponds. as are all readings.

              rick j


              • #8

                koi4all: I am hoping those 50 are really small ! Seriously, I think raising little ones to see what happens in their development is a fascinating part of this hobby. A weekly 10% water change may be just right or it may not. It is really not the percentage that counts. It is a question of what is needed to maintain water as low in contaminants as is practical. Nitrate adversely affects growth rates, but the culprit that has been studied a good deal in other species is the hormone/pheromone levels. Adult fish produce more, but all produce some. These hormonal contaminants retard the growth potential and are not filtered out by mechanical or biological systems. There is some indication that activated charcoal can help, and maybe more advanced research since I last looked into it. The only reliable means to control the hormone levels of which I am aware is to change out the water. Unfortunately, there is no test available for hobbyists to measure hormone contamination.


                • #9

                  Dang, I thought you had a hormone/pheremone Tetra test kit to suggest. It is a shame that so much of what we do is based on experience instead of quantifiable analysis. Perhaps that makes us artists? (50 to go to catch up with Mark)

                  Jeff R.


                  • #10

                    Catch up

                    How many water changes does Mark do? Or, do you mean he has a test kit?

                    ..... You couldn't mean you want to catch up with his postings. In all things koi it is quality that counts, not quantity. Besides, he'll never let you catch up. (After oyagoi, will he die at the next spawning?)


                    • #11

                      I had to bump this "last page" of threads.......for all to see.

                      I was just I started going back and looking at THE TOTAL NUMBER of pages of threads from the beginning of time for KOI-BITO. I ended up at 557 pages. WOW!!! The very next thing I noticed was that MikeM has been here from the beginning. December 2003! How AWESOME is that! Many, many, many thank yous to the diehard "Daihonmei". And he keeps on ticking....12 years here and still going.

                      I was actually shocked that I joined in August 2004, a newbie. AND 11 years later......still a newbie

                      Thank You Brian for starting this up and everyone for making this possible. I really do miss the KOI-BITO magazine issues. I still have them under lock and key at home.


                      • #12

                        Akai-san, you are not as much a newbie as you seem to think you are.

                        And, how appropriate that going back that far you get me posting about water changes. That is a fundamental of koikeeping on which my views have not changed, although my weekly water change is now around 35-40% rather than the 50% rate used with the old pond I had in 2003. To get the best out of the genetics of a koi, the water is the first priority.

                        Yes, I have been on K-B since close to the beginning, but not from the start. When I first joined, Brian had established K-B to supplement the magazine. It was akin to what Nigel Caddock had done in creating the old NI board (long gone) as a companion to Nishikigoi International magazine, the leading source of information for the western koi hobby in its day. Dick Benbow and some Brits were purposefully posting back then to get the board going. I do not believe those very early threads still exist. Perhaps lost in an early upgrade? Activity on K-B has declined substantially over the past few years, as it has on other site-based forums. The action is now on Facebook, some in FB groups and much more with followers of particular breeders/dealers/clubs/etc. For the latest news about shows or harvests, FB postings are in the lead by miles over forums. However, most of what is on FB lacks substance. When substantive matters do get posted, there will be some replies, but over the course of a day or two, it is all lost in the mass of trivia. Try to find something you recall from a year ago and you fall into a rabbit hole. I see a great deal of misinformation on FB, but it is impossible to try to correct it and attempts are usually not taken in a spirit of learning. I have seen inaccuracies get 30 'likes', probably because there was a pretty picture. So, while activity may be down, I still find K-B and the couple of other koi forums are a better source for learning because discussions can occur in depth and old discussions can be located. FB is too ephemeral and often commercialized. But, it is instantaneous, fun, newsy and all the 'likes' make folks feel good, even if half the time they don't know what they are talking about. .....I'm showing what an old guy I am.


                        • #13

                          So is this thread the old timer's convention?

                          Mike is to be commended for his long time contribution to this site, and koi keeping in general.
                          Koi keeping is not a belief system; it is applied science with a touch of artistry.


                          • #14

                            Remember, what was that social site Rupert Murdoch bought (*ster was it?) I can't even remember it. Facebook, too many pics of poorly-shot food. Koi pics- nice, but still pictures don't capture fully the actual beauty. So what are we missing not being on FB? Koi-bito is where you get ideas explained and where you learn. If you can't read and write, go ahead, go and click "Like" as fast as you can on Facebook. Thanks for the posts all these years. Glad KB isn't too popular though, it feels like it's cracking at its seams already.


                            • #15

                              Also the social media experience is about right here, right now. No perspective on what others said yesterday, last year, or 15 years ago. There is no serious archiving and very little search support. No real substitute for proper BBS on any given subject. What I really don't like on the koi FB sites is no one stops those damn posts of the water garden supplies pushing their damn lilies. And there was on guy proudly showing off the Aquacrap style pond that was maybe 3' at the center, no BD, and full of rocks and gravel. And the comments where intelligent things like "ain't it purdy". If you try to post a list of good koi reference get a silence....because you imply people should actually spend money on books......are READ THEM. Shocking.
                              Koi keeping is not a belief system; it is applied science with a touch of artistry.


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