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  • Momotaro Fish


    Perhaps this has been answered before but I cannot find it on the forum. I have been told that these beautiful very fast growing fish are really only suitable for heated ponds.

    Does anyone know if this is so and if so why?
  • #2

    I think people who invest in this kind of show koi needs to protect their investment by encouraging their continued progress which yes, does mean a heated pond. Does it mean at some time you can begin to expose them to lower temps after they've reached their potential. yes, but keep in mind koi are not cold water fish.
    temps like in California and Florida would be fine for most winters. But you can't ship one up to canada without some kind of controls. here in the northwest, mine don't see anything lower than the 50's. these are decent koi from Niigata
    but certainly not eleite jumbos.
    Dick Benbow


    • #3

      Kois eat more and grow faster in higher temp. Momotaros like Sakais are from the southern part of Japan (Okayama and Hiroshima respectively) and their main feature is growth rate which one is paying for as well. Therefore it doesn't make sense not to allow them to continue to grow at their potential in a heated pond.


      • #4

        I think it's not a matter of just Momotaro fish being suitible for heated ponds, any koi can be kepted in a heated pond, it just depends what part of the country you live. Here in San Jose California hobbyist really don't need to have there ponds heated, but to each is his own. If your fish are at a level to be worthy to be kept at 70-75 degress all year around so do it.
        The world sleeps as the chance to learn something new passes.


        • #5

          Everything I have read from experienced koi keepers and dealers suggest that the koi needs too go through a winter fast but not one that compromises the koi by subjecting it too extreme low temps.
          Most suggest temps in the mid too low 50's for around 3 weeks too 3 months and then gradually bringing them out of it.
          By keeping them at warm temps year round you will be asking for trouble especially in the older more sexually mature koi.
          Since I don't have the hands on experience yet it was expalined to me that they need this winter time too reabsorb eggs and rest, and it also benefits the skin quality.
          Am I off base here?


          • #6

            Whether produced in Niigata or Southern Japan, koi are still temperate climate animals that are seasonal in nature (ask JR and you'll get the full treatment about this :-)

            Essentially what this comes down to is that koi need to experience winter. Not necessarily a blistering icy winter but enough of it to trigger their hormonal cycle. Momotaro himself said that koi that experience a colder season without food typically catch up in growth with those that are fed year round.

            A koi's metabolic system is optimal at the high seventies, low eighties (°F). What I do is use a pond heater to follow the daily average temperatures and not allow a cool off during the night in the growing season. This allows the koi's metabolism to remain fully active during the growing season.

            I maintain a minimum of 65°F year round except when the koi are supposed to get their "winter". Here in the Pacific Northwest I make that correspond with the coldest months (to save $$$). So in January I gradually lower the temperature to the low fifties and maintain the koi there for 6-8 weeks (depending on weather) without food.

            After this "koi winter", I gradually raise the water temperature to 65°F over a two-week period, over which I start to progressively increase feeding to once a day. Then I let nature catch up and again keep up day temperature at night using the heater.

            I hope this helps.


            • #7

              This is getting to be an interesting topic.

              We in the equatorial region are thinking of chillers to modify our pond temp. Has anyone come across any articles to suggest which is better ie creating a scenario of the 4 seasons or have a constant heated pond temperature all year round? Interestingly we know the better fish of most breeders are being kept indoors in heated ponds during the cold seasons. Anyone has any idea what temp do they keep them at? Only 2 weeks ago Kentaro-san from Sakai Hiroshima was at my place when I asked him regarding pond temperature. He suggested we in this region (Malaysia) should have pond temp at 26degC alternating with 28 degC every 2 weeks. His rationale is better control of the feeding & growth frenzy, better shiroji and beni, and overall better skin quality.


              • #8

                Over many years in this hobby, I've heard much said about 'giving the Koi a Winter'.

                Also though, I've heard a lot said about not killing off your filter bacteria.

                Therefore forget the koi and concentrate on the filter bacteria and at a temperature of 14 degrees, the bacteria will be maintained. Below this they will receed.

                Any thoughts?
                Regards, Bob
                ><{{{{º> ><{{{{º> ><{{{{º>
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                • #9

                  Hi All

                  Thank you for your really interesting replies. My pond is heated but I am quite far north (Northern Ireland to be precise) and not all the ponds in my area are heated. It has only been brought to my attention recently that some Japanese koi may not do so well as others in unheated conditions.

                  I take your points/comments about the bacteria, however, I had thought it was more to do with genetics?


                  • #10

                    dbth: Your question makes wish I had kept notes of a post by JR giving winter greenhouse temperatures. My recall is that temperatures in the mid-50sF down to perhaps 49F were common in Niigata, but that some breeders maintain temperatures in the 60sF and higher to continue growth over the winter months. JR has indicated that a 20 degree drop (F) from the high temperatures of summer to the lows of winter is sufficient to bring on the hormonal and metabolic changes of a seasonal winter, if accompanied by fasting for a period of 4-6 weeks. I do not know the source of his advice on the subject, but I accept it because of the reliability of his views on other subjects. However, I keep my eyes open for other information specific to koikeeping in warm climates since so little is written based on actual experience.

                    I also seem to recall Maeda commenting that a female koi that had become too full of eggs needed to be spawned to get her in proper shape. (I do not recall if it was in an interview or on Brian's DVD, but I think it was in a printed interview.) It stood out in my mind because typically koi being raised for show would not be spawned. Fasting would be preferable to the risks of spawning such a koi, I think.

                    The use of chillers on a pond, now, that is something I would be curious about. But, in my area of Florida a 20 degree water temperature drop over the course of a year occurs naturally.


                    • #11

                      MikeM you're quite righ about what JR said (I trust him too :-): a 20°F difference will trigger the hormonal cycle. And yes, it is better to try to have show quality female resorb their eggs over "winter" than to have them spawn.

                      Bob, I do not recall the 14°C figure, maybe you can elaborate. The fact is that autotroph bacteria best thrive at around 85°F, our koi do best at around 78°F (at which level bateria may do something like 80% of their best). The lower the temperature, the lower the multiplication rate, and the lower bacteria count (assuming the same feeding level, which is not true: lower temperatures, lower feeding). So to a certain low point the bacteria level will follow the feeding level (available bacteria food).

                      Below 65°F bacteria activity/multiplication really slows down; this is why the recommendation is to feed only once a day under such circumstances.

                      I have read reliable reports of bacteria activity as low as 47°F. Bacteria are much better at survival than evolved animals. For example, bacteria survived on the Moon for several years in extreme conditions of cold and heat, and were revived by NASA as soon as put in a favorable environment for just a few days.

                      Bacteria in filters will enter a survival mode as soon as food and/or temperatures drops below a certain level. In such mode, inactive bacteria will be generated whose sole role in to carry the species into the future. They will start a new bacteria active colony as soon as conditions are favorable. That is why an establish filter starts up faster in spring than a new filter would.

                      I hope this helps,


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