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  • Results 1 to 7 of 7

    Thread: Some questions about somatostatin

    1. #1
      SimonW's Avatar
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      Some questions about somatostatin

      Hello friends:

      Now all my koi are in the small over-wintering tanks. They are very crowded to say the least, but I keep up the water quality by constant water change through trickling new water into the tank.

      My concern is about their growth, mostly as it is said that the fish secret somatostatin into the water and more crowded it is the higher somatostatin concentration in the water, and that inhibits their growth.

      This sounds logical, but I have some questions about this issue:

      1) Isnīt somatostatin a hormon that affects the cells inside the fish body, not cells on its body surface? So it should not be secreted into the water but stay in the blood. Even if it is secreted the concentration of this hormon in their body must be far higher than that in the water, therefore in-activating it by using PP does not matter so much.

      2) If somatostatin is indeed secreted into the water and its higher concentration inhibit the growth, the fish will be less interested in food, right?

      3) I had 3 whiteish karashigoi that all grew much wider but not as much longer last winter, can it be caused by too much somatostatin in the water? The confusing thing is that small koi of other variants did not grow in this manner.

      Thanks for your thoughts!

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    2. #2
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      One more thing:

      4) Somatostatin is a peptide hormone, which means that it requires receptors to get into cells and/or fish body/blood. It is highly unlikely that the cells on the fish skin have this kind of receptors, as these cells do not affect growth.
      Last edited by SimonW; 11-14-2021 at 04:37 AM.

    3. #3
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      PP or chlorine should destroy it.
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    4. #4
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      Quote Originally Posted by KoiRun View Post
      PP or chlorine should destroy it.
      Thanks for the info, though my question is whether there is significant amount of somatostatin secreted into the water so that PP or chlorine treatment is necessary.

      My earlier understanding was that fish secrets somatostatin into the water, and the more dense the fish are, the higher somatostatin concentration in the water, thus more inhibition of the growth. Then PP or chlorine treatment will remedy the problem.

      My current understanding is that fish donīt secret any significant amount of somatostatin into the water. Instead the crowdedness triggers stress for the fish, therefore the fish will have higher somatostatin concentration in the blood which in turn inhibits their growth. Therefore PP or chlorine treatment will not remedy the problem. Meanwhile if stress can be reduced it is possible to have good growth despite of high density.

    5. #5
      KingstonKoi is offline Senior Member
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      Your questions are on the more scientific side, but it's an interesting question. There's an article at https://koiorganisationinternational...d-somatostatin by an Australian vet that states the hormone limits the growth of koi and goldfish. It doesn't go into the scientific detail of your questions, but it does state "if partial water changes are not performed regularly, this hormone can build up and suppress the goldfish itself." And that it serves as a survival mechanism to limit growth so the fish do not outgrow their pond.

      Seems like there would be two corollaries from this. First, the more fish in the overwintering tank, the higher level of somatostatin just based on the number of fish. Your question is "Does stress make it worse?" But just by overcrowding, you are increasing the potential level of the hormone.

      The other is that since you are addressing water quality by "constant water change through trickling new water into the tank," you are pushing out the hormone-laden water on a continuous basis. I was taught if I wanted my fish to grow, even if they weren't overcrowded, I needed to more frequent water changes. With continuous water changes, you may be taking care of the issue already, assuming there's a good turnover daily.

      I'll let those with a more scientific background address the stress question. Potassium permanganate (PP) is known to destroy the hormone, but if you have chlorine in the water, it should be neutralized for the safety of the fish. Perhaps KoiRun is saying that treating for the chlorine will also destroy the hormone?

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      Paul Sabucchi is offline Senior Member
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      This is all very interesting and brings me back to my days keeping discus, probably the closest thing in indoor fishtanks to compare koikeeping with. With discus too we look obsessively at size, shape and pattern (and high purchase price). With those too you hear of "pheromones" that stunt growth -but as far as I am aware nobody has ever actually identified these substances, as in proven it is substance such and such that causes this effect, here is the chemical formula.
      It is undoubted though that when I fed my baby discus 6-8 times a day (with 100% grated wild Alaska salmon) and changed 75% of the water at least once a day (in a 400 liter bare bottom tank, also syphoning it down and wiping the inside of the glass) the discus grew to fruit-plate size. If I fed them twice a day and changer 2/3 of the water twice a week they grew less than 1/2 the size.
      Is it simply the matter that to grow big you have to feed a lot and this causes poor water quality so in order to maintain health (and hence growth) you had to change a lot of water?
      The famous Swiss breeder Piwowarsky years ago built the most sophisticated water purification/recicling system known to man just to decide it was best to go back to old fashioned water changes. I am sure that with all the interest there would be to find a way to get discus to grow other than changing stupid ammounts of water every other minute the big discus farms would have found it. So untill someone proves there is a specific substance that stunts growth I continue to believe that overcrowding stunts growth through poor water quality, as in an accumulation of waste inorganic substances, desolved organics and increased bacterial counts with consequent poor appetite, poor health, increased risk of infections and parassite problems. But this is just my 2Ē
      Last edited by Paul Sabucchi; 11-14-2021 at 05:06 PM.

    7. #7
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      Quote Originally Posted by Paul Sabucchi View Post
      This is all very interesting and brings me back to my days keeping discus, probably the closest thing in indoor fishtanks to compare koikeeping with. With discus too we look obsessively at size, shape and pattern (and high purchase price). With those too you hear of "pheromones" that stunt growth -but as far as I am aware nobody has ever actually identified these substances, as in proven it is substance such and such that causes this effect, here is the chemical formula.
      It is undoubted though that when I fed my baby discus 6-8 times a day (with 100% grated wild Alaska salmon) and changed 75% of the water at least once a day (in a 400 liter bare bottom tank, also syphoning it down and wiping the inside of the glass) the discus grew to fruit-plate size. If I fed them twice a day and changer 2/3 of the water twice a week they grew less than 1/2 the size.
      Is it simply the matter that to grow big you have to feed a lot and this causes poor water quality so in order to maintain health (and hence growth) you had to change a lot of water?
      The famous Swiss breeder Piwowarsky years ago built the most sophisticated water purification/recicling system known to man just to decide it was best to go back to old fashioned water changes. I am sure that with all the interest there would be to find a way to get discus to grow other than changing stupid ammounts of water every other minute the big discus farms would have found it. So untill someone proves there is a specific substance that stunts growth I continue to believe that overcrowding stunts growth through poor water quality, as in an accumulation of waste inorganic substances, desolved organics and increased bacterial counts with consequent poor appetite, poor health, increased risk of infections and parassite problems. But this is just my 2Ē
      Thanks for sharing your thoughts with me. Discus-keeping seems to be very demanding indeed!

      I am now having the same thought as you do. That PP-treatment promotes growth is probably due to a general improvement of water quality.

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