Quote:
Originally Posted by
MikeM 
I have been seeing a number of references to 'baby sumi' on the boards lately. There seems to be some confusion over what is meant, perhaps because people use the term in different ways.
When I refer to 'baby sumi', I mean the temporary sumi that provides camouflage to young koi. This is a passing accumulation of melanin in the superficial layer of skin. It is seen in the Utsurimono, Sanke, Bekko and other varieties that have not had the black pigment bred out of them. It often is not present in new hatchling fry, but appears as the fry begin to look like a fish. It is commonly present in small tosai, and generally has faded away by the end of the second growing season. Baby sumi can be very black to the eye on a small tosai, but often is more a smokey, charcoal gray 'over wash' by the time a tosai has reached the marketable size hobbyists see in a dealer's tank. People get the idea that the sumi is coming up and the fish will get blacker, when in fact the superficial baby sumi is fading and the fish will become lighter. Of course, there can be instances of 'arrested development', with the baby sumi remaining longer than normal to muddy the appearance of the fish. And, there is 'adult sumi' that is undesirably weak and limited to the upper skin layers.
The sumi we want to focus on is the sumi that will create the black patterning we enjoy in adult koi. That sumi is not limited to the upper skin layer. It goes deep through the skin layers and thickens as the koi matures. Whether it will thicken sufficiently to please the eye is the future we want to be able to predict.
Since baby sumi and the shadows of future mature sumi can be present at the same time in tosai, it becomes a real test for observation. You may read about sumi 'going down' in young koi and then returning in different places. This is as accurate a description as saying the sun rises and sets, when actually we are observing an effect of the Earth revolving. The temporary camouflage of baby sumi fades away as the young fish grows. The adult sumi consolidates as the fish matures. Two different processes.
These are generalities. Individual lines will have their own idiosyncracies, and each fish is an individual. The breeder who knows his lines and has observed the development of many hundreds of thousands of his fry, has the experience of observation that no hobbyist will match. But, understanding that what appears on the surface does not necessarily relate to the beauty within, is an important point in understanding the life-long metamorphosis of koi.
I hope the more experienced among us will add to my thoughts. Whether sumi is coming or going creates so much doubt among those who purchase young fish.