Ozekoi.com

Size DOES Matter !!

This is one aspect in the hobby that I have been obsessed with since very early, but only recently I am able to achieve the growth I was aiming in the beginning of the hobby. Unfortunately when comparing to the good Japanese Koi breeders are growing their stocks now, it is very much the case of a “moving goal posts” and I am just as far behind as I was years back L.

But not all news is bad news, one thing that we as Australian Koi hobbyists must do is to appreciate what we have on our side. Our climate is perfect, our winter is not that cold and our summer is long enough without being too hot. Spare a thought on our friends in colder regions that are installing water heaters to keep their Koi alive in winter or any hobbyists in tropical regions having to add ice blocks in their ponds to cool their water to finish and prepare their koi for show. We also have reasonably good water and although some water restrictions may apply at times, with the advancement of the filtration technology, some of the shortcomings of smaller water changes can be minimized.

However not enough of us push hard and aim to grow our fish to its full potential. Our Koi clubs are not promoting large Koi as I believe they should, local shows contain mainly smaller size Koi. “4 years old and 40cm” should not be considered as normal anymore!! I truly believe we can expect for most of Koi stocks in Australia to grow to around 60cm given the proper environment, so the “blame” should be back on the keeper and not on the importation restriction or existing Koi gene pool. If none of your fish is growing to that size, take a close look at your setup and re-evaluate your growing techniques.  

Below is a guideline of what most Japanese breeders achieved on their growth rate:

Up to 12 months old – 30 cm

12-24 months old      – 40cm

24-36 months old      – 50cm

36-48 months old      – 60cm

48-60 months old      – 70cm

Then 2-5 cm / year after.  

In the last 3 years I have tried and implemented a few ideas that I learnt from fellow Koi Keepers locally and over the net and I think these has contributed (to some extend) to the growth rate that I have lately achieved on my fry and young fish which is either as good or better than the list above. However I am still struggling to grow my older Koi (4yrs on) as per guideline rates above. I am hoping my young Koi as they have not been "stunted" will maintain their growth rate as per guideline above. These are a few points that I trust contribute to the results:

1. Starting with approx 1x7days old fry per gallon of raising tank, thanks to Mr. Schnell who's proven this theory year on year. As I only uses 4000L tank, I start with 1000 fry (actually counting them). At 7 days old, 1000 of them do not seem much (fit in my coffee mug nicely). Now I can expect to have 5cm fry in 4 weeks. In 4 months average size should be 10-18cm and 6 months in 20-25cm. After 6 months normally we are entering our winter cycle which slows the growth. By the following spring a further 5-7cm should be achieve. Heavy culling along the way.

2. Soft water (50ppm-70ppm) and maintain reasonable carbonate hardness (70ppm-90ppm). Of course pH at 7-7.6 and maintain water quality to be perfect at all times by making sure all types of debris in pond, sediment and filtration tanks are taken out of the system at least every 7 days.

3. Aeration - aeration - aeration (as important as "location" in real estate). Every pond must have an air pump/blower working, plus ensuring their water returns are via either venturis or waterfalls or anything that add oxygen in the water.

4. Stocking rate of at least 1000L per 40cm + Koi. I would prefer to give 2,500L-5000L per 60cm+ but I am also struggling to maintain the number down.

5. Good, high protein food in warmer/growing period. I am mixing a 44% protein sinking food with my regular 35% floating type in my 2003-2004 growing season with promising result, especially on the body shape of the larger male Koi. Also allowing 20 minutes feeding time seems to give my older and slower Koi enough time to munch enough. If possible it is beneficial to separate the small ones (40cm or less) with the large ones as the smaller Koi are much faster in feeding. 10 minutes feeding time is enough in ponds with smaller fish only, to ensure they are not being overfed. In the spring time, always check the water parameters 3/4 hours after feeding. Perfect reading indicates your filter is coping with the feeding regime. Otherwise cut the amount of food.

6. Water changes, 10-15% fresh water/week would be beneficial but the very least as much as allowable by local water authorities.

7. Constant medium current, and incorporating the idea from UK hobbyists, I change the direction of the current every 7 days. It is said the Koi being kept in ponds (small and round especially) with the same direction of current can develop uneven body shape due to the muscle developing unevenly.

Back to the Japanese Koi Breeder :

While most Niigata breeders are very much Koi farmers, there are two “industrial scale” breeders, one in Hiroshima (Sakai) and one in Wakayama (Momotaro) that pushes the boundaries of Koi industry.

 Here I have included some of Momotaro fish from their web site (with permission from Mr. Maeda) – check their size and age !!!

Isn’t it about time we do something with our growth rate ?