[bekko]

Luke,


I'm the junk koi breeder Mike T refers to and I'm here to try to give you a genetics lesson.


First, let’s define "flawed koi" and "defects". I assume we are talking about deformities here. Every koi has flaws and defects - the grand champion could always be just a tiny bit better. Obvious physical deformities are another matter all together. Fish with obvious deformities are always the first to go. These include flared gills, missing eyes or fins, bent heads, scoliosis, etc. I have never heard of anyone selling koi which are obviously deformed. You can't even sell deformed koi as feeder fish because the consumer is afraid a deformed koi will make his oscar or arowana sick. I suspect most deformities are culled by Mother Nature in the process of rearing fry. The most heavily deformed cannot nourish themselves or cannot compete with their siblings and perish early. Fish with obvious deformities, but which live long enough for someone to look at them (the first cull), are tossed immediately.


There are all gradations between the koi which is obviously deformed and the koi which has "perfect" confirmation. I say "perfect" because it is such a subjective thing and reflects as much the eye of the artist as what is best for the fish. Some fish have obvious deformities. Others have such subtle deformities that we no longer call it a deformity - we call it poor confirmation. Is a fish with a thinner tail tube deformed? At what point do small pectoral fins cease to be called "small" and start to be called "deformed".


Deformities are common in koi and in any animal which produces very large numbers of offspring. There are deformities in wild carp offspring although we are unlikely to ever see them because they are less fit to survive and will perish early. I assume that there are fewer deformities in wild carp than there are in koi though. This is an unavoidable artifact of the domestication and selective breeding process. We do not demand that our koi be able to compete out in the wild and we provide an environment where a weaker individual can survive. More about in-breeding depression in a minute.


Every breeder, even the backyard breeder like me, uses the best koi at their disposal for broodstock. Rearing a batch of fish is a lot of effort for precious little reward so only a masochist would do otherwise. Many of my broodstock are four generations removed from Japan - but that is not the important consideration. Of more importance is how much selection was done to arrive at that parent fish. I suspect a really good brood fish, like a really good show fish, is out there in the range of one in one-hundred thousand. In other words, about 100,000 fish were looked at to arrive at that selected individual. Of those other 99,999, most were thrown away as juveniles because they had deformities or because they did not have enough color to make it to market. Others made the grade to be marketable, but are of lesser quality than a show fish or a brood fish. Of course, most of the fish which are born are never even looked at as they perish before the first cull.


I have a big back yard, but do not have the space or time to look at millions of fish each year. I can look at about 10,000, feed most of them to the pigs, sell a few thousand at grade 'C', keep several hundred for up to a year, and keep ten to twenty for several years. Thus, my very best fish is not likely to be as good as a real breeder who can look at (or pay people to look at) millions of koi each year. Nonetheless, even the best breeder using the best broodstock is going to throw away a LOT of fish. Koi do not breed true and never will.


In an attempt to get any type of domestic animal to breed true you have to do line breeding (i.e. in-breeding, breed siblings, mother to son, etc). You also have to keep selecting for the same desirable characteristics over and over. In koi, most of these characteristics are polymorphic with contributions from many places along the genome so it is not a simple on-off switch. There are different levels of dominance and recessiveness associated with each characteristic as well. Most of the desirable traits in koi are recessive which means they will usually be masked and are only occasionally displayed in the phenotype that we see.


With some animals, you can weed out the undesirable characteristics and get to a point where almost all the offspring have the desired look. In other animals, like koi, before you can weed out the undesirable characteristics the line becomes "weak" through in-breeding depression. In-breeding depression happens because in selecting for desirable characteristics, you inadvertently also select for characteristics which are undesirable. In many cases this is unavoidable because these undesirables are so closely associated with desirable characteristics on the genome. When the line becomes "weak" due to in-breeding depression the rate of deformities becomes excessive, the fish may be stunted, etc.


To recover from the in-breeding depression, it is necessary to do out-crossing. Out crossing brings in relatively unrelated genetic material. Out-crossing results in an inter-varietals type of hybrid vigor (not species hybrids, but varietal hybrids). This renewed vigor strengthens the line in terms of reducing the number of deformities, the fish grow larger, etc. However, it also dilutes those desirable characteristics which the in-breeding process was selecting for.


So, it’s a tug-of-war going back and fourth between in-breeding and out-crossing. You make a little progress with in-breeding, and then have to out-cross to strengthen the line and most, or all, of the progress is lost. The overall rate of progress is, thus, extremely slow. Because of polymorphism and the varying degrees of dominance/recessiveness for koi characteristics, the genetics are exceedingly complex. Simple Mendelian genetics, science and math become almost useless and the breeder must rely on art, intuition and trial-and-error.


To make things even tougher, the best show fish may not be the best brood fish. Sometimes a pairing of fish which do not have the best patterns have genotypes which just seem to click and they throw a larger proportion of show-quality fish than other pairs. These broodstock can not be considered flawed or defective despite their less-than-perfect patterns. They are the right fish for the task at hand.


It is my opinion that the only way to avoid large number of deformities and culls is to find a completely new paradigm for producing koi. We will have to shift from typical selective breeding programs to transgenics and/or cloning technology which does not presently exist. When it comes, the impetus and rational will be based on economics, not the need to kill fewer fish.

Mike T,


My friend, I am offended. I may have junk fish because of the limited numbers I am able to produce and select from (as discussed above). However, I do not consider them mutts. Mutt implies a mixed breed heritage. Pond mutts are what you get when your yamabuki spawns with your sanke. Junk fish are what you get when you cross a one-in-a-thousand kohaku to another one-in-a-thousand kohaku.


Also, I need to talk to you about curing bamboo. Will send e-mail.


steve hopkins