Average Growth rates in Japan

[farne230]

I would like to know what the average or expected growth rates for non-jumbo and jumbo koi are.

At end of first growing season;
At end of second growing season;
At end of third growing season;
At end of fourth growing seson;
and so forth.

[ppp]

A whole host of factors may influence growth rates, even in Japan.

1. The bloodline of the koi - This is self-explanatory.
2. The type of koi - Ogons tend to grow bigger and faster than gosanke. Doitsus and gin rin varieties, on the other hand, tend to not only grow slower but also max out at shorter lengths.
3. The grade of the koi - Tateshita and general grade koi will register lower growth not only because of poorer body structure (as compared to tategoi) but also because of the significantly higher stocking levels of the ponds/mud ponds they are put into.
4. Show circuit - Some koi which are strong contenders for shows at smaller sizes are put into tiny ponds to restrict their growth and maintain their level of finish.

Having said all that, I think the general guideline for a high quality good bloodline healthy gosanke brought up by a breeder (as opposed to hobbyist, to remove the extra variable of pond conditions) in Japan would be:-

30-45cm after 1 year
45-65cm after 2 years
60-75cm after 3 years
70-80cm after 4 years
75-85cm after 5 years

This assumes the koi is put into mud ponds for 5 months a year, particularly in the first 3 years.

Obviously, not all gosanke actually pass the magical 80cm mark and many may max out growth at 65-80cm in hobbyists' ponds.