Understanding sumi on a deeper level        

                         By James Reilly USA ZNA District chairman

 For those veterans in the koi hobby and show ring, talking about ‘Sumi’ is a pretty common conversation. But I’d like to challenge our ZNA judges to take the next step in understanding sumi.

  We have all been educated as to the different types of sumi—we have diligently learned the Japanese terms, the breeders who introduced the types, the varieties that show these variations and we have even mastered the Japanese expressions of different tones and expressions for the basic color of black!

 And to those that have made this journey and know their ‘sumi’ I salute you!

 I have always found it both fascinating and rewarding to learn the old Japanese ways and explanations and then apply western biology and physiology to the lesson. For me it completes the circle and the lesson. What I have found in addition to that however, is that a greater synergy of understanding occurs when one has all dimensions of a subject in place.

  In the case of ‘Sumi’ let’s see if we can’t assimilate some basic science (genetics in this case) into the Japanese explanation of what is ‘good’ sumi and what is weak sumi.

 Before we get into the actual point of this lesson, we need to get some basic physiology down—

  Sumi is a color cell. Typically found in epidermis, upper dermis and lower dermis, these cells (melanocytes) are often found amongst the fat cells of within the dermis. These cells can be large or small, numerous or sparse, dense and linear in arrangement or thick, dense and deep in concentration.  These cells can also be covered and associated with luster crystals or with luster cells. And these sumi cells are storage facilities of naturally produced melanin.  Melanin is a pigment that is derived from tyrosine, a common amino acid.

   Melanin itself is a common component of living things. But in koi it is both a natural and selectively bred for trait.

  And here in lies the deep lesson of sumi--- Sumi can appear naturally in individuals and they can be selected for to intensify that trait in future individuals. OR sumi can be better than even the results of twenty years selective breeding when it is derived from natural mutation.  In short, when it comes to selective breeding results verses nature’s mutation for strong sumi we might say that “you can’t make a sumi mutation ‘silk’ purse out of a selectively bred ‘sows ear’! 

 To appreciate that statement let’s look at what actually happens when a gifted eye selects for sumi trait. In this case, we find an individual with nice sumi. We breed this fish in order to ‘introduce this trait into its progeny.  And we patiently select the best offspring and repeat the process. This results in individuals that represent the best of the best within that gene pool. This is, in short, an effort to concentrate the amount of melanin in the skin thru the intensifying of cells and cell type.

  Now let’s compare that to a natural mutation for good sumi. If you refer back to the points above regarding melanin being a natural metabolic function of simple amino acids to form pigment, what would happen if an individual was born with a mutation in this area?  In this case, the animal or fish is born with a mutation defect that causes the individual to over produce tyrosine or in other cases, to be unable to ‘turn off’ production. In this case, we can’t stop strong sumi! Indeed it is harder to breed this ‘out’ than to breed sumi in’!

  At this point the bright bulbs reading this will be saying “Ahh ha!!! So THAT is why he keeps going on and on about those principles 1-2-3 etc. ALL koi do have a black or a white base”!

   This is also why the early asagi and the lowly Karasu goi are such important lessons in understanding color in koi. Each represents the living battle of melanin and its war with ‘no melanin at all—IE Leucism. As a side note: this makes shiro utsuri an amazing creation.

  So melanistic forms bring us the very best sumi types. And selective breeding of melanin cells only can produce so much. Instead, selective breeding of individuals that possess genes for hyper-melanin (heterozygous) are important building blocks to excellent sumi (dense, deep and shiny).