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Comments on reaing koi fry in green water.

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  • Comments on reaing koi fry in green water.

    Hello all Need some imput here. For years I have read and seen the measurable attributes of raising young koi in natural earthen ponds. I personally raised two different groups from same parents early this summer. Three hundred or so fry were raised in an above ground tank 12x10x4 with lots of mechanical and biological filtration as well as uv sterilization...basically gin clear water in a very well controlled environment. They were fed on a heavy diet of freshly hatched artemia for the first month than switched to a standard pelleted food that I pulverixed to accomodate their size. The second group were released into an earthen pond 40x20x6 feet deep in their second week and were left to their own devices for three months,with occasional pelleted feedings after the first month and a half. Although the first tank raised group were healthy, they had not achieved near the size or the color of the second pond raised group. What I propose to do next spring, is to raise the next batch of fry in a 24x10x4 foot deep above ground tank with seasoned green water. Will probably use only airstones the first few weeks with a small intank pump hooked to a spray bar that will run the length of the tank to provide a minimal amount of current.Soon after, I will switch over to main pump that will run through the three barrells of strictly bio balls with no mechanical filtration as I want to try and duplicate the earthen ponds as much as possible within my limits of course. was also considering putting four clumps of (Sodium) bentonite clay in each corner of pond in the hopes that the fry may be attracted to nibble on it from time to time. Ther reason that I am using the sodium and not the calcium is that I have been told that it will swell and become more like clay, and will remain stationary in the corners.???????? My only concern is the health of the water bacteria wise. It will have ample amount of circulation once the main pump is started and I believe that the force of the return should more than aireate the tank. Also the bio conversion tanks should handle the fry up to culling point. I have seen many pictures of these growing ponds and with the exception of occasional airationpumps and feeding it looks like they are leaving the rest to mother nature. I have a test group of about thirty culls 2 to 4 inches in the tank now with no bio yet. Will hook those up soon. They all seem to be feeding well and most are still hand feeding. Was hesitant to put any of my kohaku fry in there until I got some feed back from the group. The whole point of this experiment is to see if the more natural environment of green muddy water will continue to enhance the colors of my kohaku youngsters and to see if I can duplicate the results of the mud pond on next springs hatch in my back yard. ALL opinions critisisms and suggestions are encouraged and appreciated. I will of course keep the forum updated on results. Thanx to all, Kiefer
  • #2

    Well it looks like your having some fun and learning to boot!

    I think your experiment will find that as far AS THE KOI CARE, they will choose the green water every time.
    the skin will be better and so will the growth.
    But know that in green water if you have a problem you'll have a more difficult time discovering it quickly.

    usually the Ph of a green pond runs higher and with the accelerated growth you can push some seemingly decent beni "over the edge".

    everything considered, my best luck has been with natural green ponds.
    I think you will gravitate that way as well.

    thanks for taking the time to post for us. your efforts are appreciated.
    Dick Benbow


    • #3

      Hello Dick,

      I have used the natural mud ponds and would agree that it is a tried and true method. However, am trying to duplicate these conditions in a more controlled environment to eliminate preditory problems as well as being able to cull more often to seperating the shooters as they are called here or toby's from the others. I personally saw a pack of 3 huge tobies that were attacking schools of their much smaller brothers and sisters relentlessly and eating them by the dozens on a daily basis in mud pond.
      I feel that 1 or 2 good seinings during first month of development would help the canibalism tremendously. Understand though that I know I cannot save all of them from being eaten, but I think that it would increase the numbers of small fry for me to cull through. I would not like that decision made by some big guys appetite

      Also, arent most mud ponds green by choice? I would have no better chance detecting a problem there than in my green pond. Actually, I would probably have a better chance detecting a problem as I would be interactive with fry on a daily basis.

      If u were going to set something like this up Dick, bearing in mind that most natural ponds have no aireation to speak of and certainly no mechanical filtration, what would u do? How would u maintain the natural pond conditions as well as produce a healthy environment for the fry. This tanks sole purpose is to provide a more natural environment to aid in the developement of the koi for the first six or seven months of their life.

      Your opinions and ideas are important to this project. Spread the word and get these experts to pondering...No pun intended :wink:

      Regards, Kiefer


      • #4

        I have been struggling with a design effort for three years and haven't arrived at an answer yet.

        In the beginning when I'm dealing with very tiny babies, plenty of live food and a constant trickle in of ground water (well) helps keep the toby problem down. Since there is no filtration on this effort because of the restriction on the use of a pump, I can control the color of the water by the water feed in and numbers of babies in the holding pen. Once the babies get up around 3 weeks old the concern of toby attachs as you discribe is a real concern. This is when the babies are big enough to put a pump and filtration on the containment pond and beginning working hard with clear water and good sight to keep numbers down by contantly sizing toby's.

        It's alot of work but I actually find that one giant green pond big enough to disperse the numbers seems by fall the best results with alot less handling. I will have culled only twice during that grow out period.

        hopefully both you and i will be enlightened in a zen sort of way by someone else with some different ponderings....
        Dick Benbow


        • #5

          Good morning Dick

          I see your point. I am convinced that exposure to natural pond conditions
          at an early age directly affects there developement both color and size wise. Its a tough call. Last spring I found it very easy to monitor and feed fry in clear water with continuous feedings of live brine shrimp until they developed some size. I took them to the mud pond at 3 weeks of age. Maybe I will keep them in the clear tank a bit longer...say 5 weeks
          This may give me a better idea of who is outgrowing who and then move them into artificial mud pond.

          Do u think that this green water set up with 150 gallons of straight bioconversion would provide a fairly safe environment for the fry? Also, what are your thoughts on introducing calcium bentonite to the mix.
          There are no right or wrong answers, just great opinions!

          I am hoping that this experiment will yeild benificial data for all of us.

          Thanx again for your insight, Kiefer


          • #6

            One thing i have learned is that providing good food and water is critical for the growing fry. As koi age they absorb a lot of their bodies needs from the food. BUT as babies thru tosai the minerals they need for organ and bone growth primarily is taken from the water. I have always provided plenty of fresh water from the well during this stage. I have never added minerals to the water altho I would think it would be an excellent idea.
            On your 150 gal green tanks please keep your population to a minimum. as long as your playing around with idreas in your mind. if there was a way to say every week during the first coupla months to be able to add green water input from a bigger vessel and then wean it away to clear once a week to check on things, that would really be nice.
            Dick Benbow


            • #7

              Keifer: I am also raising some fry this year. About 5,000 I have posted the details over at

              I am also using the Artema (brine shrimp). I have plenty of goldfish flakes that I have powered up and waiting till they are old enough.

              Normally I put eggs to hatch out in my stream. They grow much faster there than koi I feed pellets too. Even sometimes I catch koi from the stream, and put them in a spot and feed pellets to and their counterparts that I left in the stream grow much faster. This stream is 50' long, 14" deep, and 4' wide, and full of plants and rock bottom and is connected to my main pond. Flow rate of about 8,000gph.

              I always have koi show up in my filter. One this year (a tobi) was 8" long. Born in June. [/url]


              • #8

                That is a great idea Dick!

                I may have not been clear RE my actual tank size. The main raising tank that is in the pic is 24' long 10' wide 4' deep above ground. The tank holding the bio media for this pond would be 150 gallons. The actual nursery that I start them off in is 10x 12x4 also above ground. I use a small in pond pump with a large foam casing wrapped in a nylon stocking pulling water from bottom and returning it through a uv and then to a long spray bar that runs the width of the tank. I could actually add green water to the nursery as needed from main rearing tank which is kept green continuously. That would give them plenty of nutrients while not haveing to turn the water completely green and would still allow them enough clarity in the water to continue to site feed on live brine larvae. Would probably want to remove the uv though. The tank is completely shaded so I dont think that it would continue to go green on me.

                I knew that if I kept nudging I would get a good idea or two out of you
                If u come up with anymore suggestions or ideas please let me know.

                I will now sit back and absorb this info and wait for more feedback (in a zen sort of way) :lol:

                Thanx, Kiefer


                • #9

                  Whats the forumla to make water green artifically ?

                  Can you grow Artiema to adulthood and then feed to the babies. I read something about a dangerous bacteria. But as the fry get larger, the number of Artiema they need grows and grows.

                  How many tablespoons of eggs a day of Artiema are you hatching out to feed how many fry ? I am hatching out 3 tablespoons a day. I check the pond at about 2 hour intervals. If I dont see any more Artiema swimming, I increase the amount that I hatch out with the next cycle.

                  I am putting the salt right in the water with the Artiema as they are so small my brine shrimp net wont catch them. Since koi can handle up to .03 this shouldnt be a problem, or will it ? The salt level should not reach that level until they are ready to be moved.

                  Also, any ideas on how to culture those fresh-water shrimps called skuds (Hyalella azteca) ?

                  Once my baby koi are large enough, I will be moving them to my 2,000gallon lower pond (which is connected to my main pond) so filtration and circulation will not be a problem.


                  • #10

                    Hey Greg

                    There are liquid fertilizer products that u can use to achieve green water but mine goes green on its own. It must be a Florida thing.

                    I have never grown artemia to maturity. I keep four 2 gallon jars of them perculating around the clock. I harvest a jar a day 2 table spoon fulls. I then pour them into a brine shrimp net and rinse them off with fresh water before feeding them to fry. I pour them back into a container of pond water then spray them over the pond with a turkey baster. Sounds dumb but works great!


                    • #11

                      The shrimp are so small they go right through my brine shrimp net. I even tried 500micron microscreen. So I just mix the quart of water with about a gallon of pond water and dump them in. Salt and all. Since larger koi can tolerate the salt up to 3pounds per 100 gallons, I didn't think it would be a problem, but I want to make sure. This is a trial spawning for me anyway. Practice for the real thing next spring.

                      So you harvest your shrip 96 hours after they hatch ? Are they bigger at that size ? Are you feeding the shrimp anything after they hatch ? I read that they become less nutritious the longer they go because they are feeding on their yolksac.

                      I am using 2 two quart bottles, and harvesting every 24 hours. I get alot of shrimp this way but they are very small. As long as growing the shrimp to a larger size is not dangerous to the koi, Id like to try it.

                      I cant get green water to save my life. I will keep looking for a formula that is fish friendly.


                      • #12

                        I feed the hatch to the fry daily. I do not feed the newly hatched brine shrimp. They are used immediately, and I have noticed that they continue to squirm and hour or two after they are introduced into the fresh water. This is good, as the young fry are sight feeders at this stage and it stimulates them to eat. The brine shrimp net that I purchased is like a white silvery cloth and works very well with the newly hatched artemia.


                        • #13

                          brine shrimp harvesting

                          Newly hatched brine shrimp are much more nutritious than older shrimp. An analogy would be the difference between alfalfa sprouts and seedlings. When they are newly hatched, the brine shrimp larva contain a rich drop of oil, like the yolk sac on fry fish. Like the fry, they burn it up while maturing enough to feed on external nutrients. You loose much of the value of the live food by not using the brine shrimp right away. It isn't dangerous, but it is a waste.

                          If you want green water, don't start with mature pond water (unless the pond is going through an algea bloom). Get fresh well or tap water and aerate or dechlor as needed. Mature ponds seem to resist algea blooms, probably because either the biofilter bacteria or the beneficial blanket algea give off inhibitors for single-cell algea. Fresh poultry manure is the traditional fertilizer used to kick-start blooms in grow out ponds.
                          Lynne in St. Louis


                          • #14

                            Lynne is right,

                            first filling was with the mature pond water and was unsuccesful. Next filling was directly from well and was green in 4 days.


                            • #15

                              what kind of fertalizers would be fish safe and make the pond go green ? I have a whole case of miracle grow rose food.

                              How turbulent of water is too much fry ? I made up a pump intake out of aluminium window screen for my 475gph pump. I put it in the hatching pond (500) gallons, and set it so the entire pond would vortex. I observed the koi fry for about 5 minutes and it looked as tho they were having a hard time keeping up with the flow, so I shut it off. Only circulation right now is two 48" bubblecurtains.


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