Originally Posted by
Paul Sabucchi
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