Interesting question. Having spent a lot of time on the Malaysian forum I've become somewhat familiar with the problems many Koi Keepers have with finding that "happy medium" of growth without compromising the health and lifespan of their pricey pets.
Having read and seen much over the past few years I am a believer in the benefits of a seasonal feeding/fasting regimen, but with the year around temperatures you guys have it would take a very expensive chiller to replicate that scenario so it must go out the window.
I think instead I might try an experiment in seasonal feeding both in quantity and content, possibly breaking the year up into trimesters or quarters, with show preparation getting it's own separate "mini season".
Using "show time" as the starting point, after the show and minimal feeding in quarantine I would begin feeding a high protein diet at 1.5-2% bodyweight per day, spread out over many small feedings throughout the day. Since you are wanting to build muscle and not fat, I would utilize foods ranging from 40-50% protein, as Koi will metabolize protein both for growth and energy. During this high growth season I would use feeds that are high in spirulina, fishmeal, crustaceans, vegetables, fruits, and grains, with a modest inclusion of silkworm powder.
After that I would switch to a diet more heavily oriented toward cleansing and purifying the skin and pigments. Reduce or eliminate the levels of spirulina, crustaceans, and veggies, with a heavier grain, and fishmeal content, and less if any silkworm. Keep the basic protein levels about the same, but feed only 1-1.5% bodyweight. Hopefully this would slow growth a bit, while allowing the fatty tissues to cleanse themselves and the skin to consolidate color into the hi and sumi plates.
For the next season, I would return to the original diet, to bulk up and strengthen color once again, until about 6 weeks before show-time. For show prep, I would slowly reduce quantities to less than 1% body weight, then .5%, and one full week of fasting. Eliminate all color enhancing food sources (spirulina, shrimp, fruit, veggies, etc...) and go with a bit more silkworm powder as a percentage of total feed. This should serve to whiten shiroji and brighten the color contrast just before the show.
Ok, I've tossed my 2 cents worth in. I'm ready to hear from some "REAL" experts now
