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What to use to kill dragonfly nymphs but safe for fry ?

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  • What to use to kill dragonfly nymphs but safe for fry ?

    I have tons of dragonflys at my place. Last July I set up a tank to hatch out and raise some fry. No sooner than I was finished the dragon-flys were already laying their eggs. Weeks later I caught huge dragonfly nymphs swimming around in there. Im sure they are eating my fry.

    Is there anything like Mosiquto dunks or something that I can put in that would be safe for the koi fry ?

    Did some searches on the web and people said that DIMILIN might work. Any side effects on developing fry ?
  • #2

    Dimilin Flo Greg, it will sort anything with an exoskeleton, but don't let it anywhere near a natural water coarse. The environment people do not like it!

    E-mail me if you have any problems obtaining some.
    If you buy it in liquid form, use 1/2 mil per ton.


    • #3

      Is that the same stuff that they sell at AES ? What about the food the fry will be eating like Brine shrimp ? Im guessing it would kill the brine shrimp also ? Infusoria, Skuds, etc ?

      I have so many dragonflys around, that just the other day, I found one that molted from an nymph on my indoor settling tank. Nymph must have came in with my filter material in November.


      • #4

        Greg, I’ve not got the AES catalogue, but it’s the same as used for Anchor worms and fish lice.

        Yes it will also take out brine shrimp. You need to get your timing right, treat with dimilin and then do plenty of water changes.

        Last year I used it for fish lice, within 24 hours, every one was dead and turned to mush.

        Your Brine shrimp are only good for a few hours in fresh water, so I don’t think it will be a real problem.
        Seeing your only working on a small scale, why don't you net the ponds to stop the dragon flies getting to your water?


        • #5

          Greg: Dragonflies in Iowa in February? I haven't seen any dragonflies around here since late November. I guess our Florida-ones get chilled when it is below 80F.


          • #6

            I was in Brooklyn Iowa a few weeks ago and it was cold as hell. It shocks me that you would have problems with dragonflies this time of the year.

            How large of a tank are we talking Greg?


            Keep it simple, keep it straight


            • #7

              I know PickleBoy is just asking now so he can have it when needed...and Yep Dimlin...get it from a local source in the "pest Control business if you can. It is CHEAP...unless it has the word "koi" associated with it.
              And yeah it will corrupt the brine shrimp...after a day...
              And of Course California has it listed as a potential Carcinogen....and I can tell you it tastes like artificial sweetner


              • #8

                alright Luke, I'll long have you been using it as an artificial sweetner.
                do mosquitos bite you and then immediately roll over dead? (LOL)
                Dick Benbow


                • #9

                  You'll bite and mosquitoes bite..... I can put to and too twogether.

                  But just let's put a warning out there.
                  "Don't sprinkle it into your pond when you are down wind."


                  • #10

                    Oh and Dragonfly Centaurs will definitely have an impact on them....

                    Then again I would think a .22 would be enough gun for most of the nymphs...or do they grow big like the Corn out where you live?


                    • #11

                      You noted the trouble with Dimlin - it will take out all the zooplankton. Without zooplankton, you have to rely on brine shrimp and such which are much inferior fry feed. I have only found two solutions: (1) predator netting to exclude the adults, and (2) precise timing. Zooplankton will develop faster than the nymphs - within a couple of weeks in most areas. If fry are stocked several weeks after filling the pond, you get the benefits of the zooplankton and the fish will always be too large for the nymphs to eat. Its' a two-way street. Large fish eat small nymphs.

                      I keep looking for a market for dragonfly nymphs. It's pretty cool to watch them crawl out of the water and metamorphose. Everyone likes dragonflys, but hates the nymphs.



                      • #12

                        No dragonflys in Iowa in february (well none outside anyway). I have one on my indoor tank in the basement.

                        Mainly im preparing for this spring's spawning. I will have various sized tanks for rearing the fry (based on the scrap liner I have available)

                        Tank #1 - 14'x17'x2'deep (3500 gallons)
                        Tank #2 - 7'x13'x2'deep (1300 gallons)
                        Tank #3 - 6'x11'x2' deep (990 gallons)
                        Tank #4 - 7'x8'x2' deep (840 gallons)

                        I have a 30x60 roll of liner left, but im saving that for customers. I hate to cut it up for breeding pools. Next year when I remodel my big pond, I plan on using the old liner 30x50 for fry ponds.

                        Im also trying to find some mud ponds, SOMEWHERE near my house.

                        Mainly I want to use the chicken shit formula and have a good green water/infusoria population ready a couple weeks before the koi are ready to spawn. Only problem with this is that the dragonfly nymphs will have a good foothold on the tank by then. If I fill the tank the same day as the spawning, then I wont have any food besides brine shrimp

                        It would take a pretty small hole net to keep the dragonfly from putting their puboskis (sp?) I wonder if I cover the tank with plastic, if that would get to hot ? That would certainly keep the dragonflys out.


                        • #13

                          Greg you can get a 5lb. bag of Dimilin for about $185. That would last you about 20 life times. You might want to think about buying some if you going to turn into a master breeder. :0)


                          Keep it simple, keep it straight


                          • #14

                            Greg, you do not put the predator netting right on the water. Raise it up off the water at least a few inches.

                            I have decided to protect my little fry ponds with one large net enclosure which will be 8-10 feet high and with a door at each end. It will keep the herons and dragonflys out while being an aviary to keep some cage birds in.



                            • #15

                              one inch or smaller squared netting raised 5 inches off the surface of the water will keep almost all the dragonfly from laying eggs in the water.
                              If you can keep the DF's from dropping their tails in the water NO eggs will be laid.


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