We are often asked, "Is there is a difference between Japanese and Domestic Koi"? Let's imagine a Japanese family from Japan. They move to the U.S. for business reasons. Are they still Japanese? Let's say they have a child born in the U.S. Is the child still Japanese? Now they raise the child in the U.S., and the child learns to speak English fluently. Is the child still Japanese? The analogy to Koi fish is the same. Domestic Koi are still Japanese Koi, but they have grown up hearing English instead of Japanese. Their gene pool is composed of the same DNA as in the Koi born in Japan. However, they may be more acclimated to the viral, bacterial and parasitic environment found in the U.S.

Koi Age: Many of us wonder, "how old is our favorite Koi"? One way to guess at the answer is to measure how long they are, and then check the Koi Growth Charts. However, most Koi have scales; thin, overlapping plates of bone that continue to grow throughout life. As they grow they do not increase in number, but rather increase in size. The growth of the scales is proportional to the Koi's growth, and annual marks are formed on the scales at the same time every year, along the outer edges. So if you look at a Koi scale, it turns out that just like trees in cross-section, they have annular rings. If your Koi has lost a scale, look at it closely, even under a microscope. Then count the number of annular rings, and your Koi is at least that old, but it maybe even older. This is more accurate for younger Koi, i.e., less than 5 years old. However, if a Koi looses a scale, and then grows it back, the new scale will not have any of the older rings. Also females may not add growth rings when they are reproducing, or grow some more after reproducing, causing 1 growth ring to look like 2. A more accurate way to judge a Koi's age is to examine the cross-section of a fin spine, which also has annular rings. The second anal fin spine is oftenused. This can be done without doing permanent damage, since the fin will grow back. The most accurate way to determine a dead Koi's age is to examine the Otolith (Williams and Bedford 1974). The Otolith is the Koi's "ear bone". Otoliths are part of Koi's vestibular apparatus, and reside in the cranial cavity. They are composed of calcium carbonate and protein. They function as sound receptors and are also used for balance and orientation. There are 3 pairs of otoliths or ear stones in the inner ear of a Koi. The largest pair of Otoliths, the sagittae, are routinely used for aging. So Otolith is synonymous with sagitta. Again you count the number of annular rings under a microscope. White bands are formed during the spring and summer months, while darker bands are formed during winter. The Koi's age can be approximated by counting the light and dark bands as one year.

Koi Can Taste: They have taste buds almost everywhere: On their lips Within their mouth cavity Their fleshy barbels (2 in each corner of the mouth) bear numerous taste buds and are highly sensitive to touch Most of their bodies are covered with innumerable taste buds, including their fins and tail

Koi Can Smell: The lining of the olfactory or nasal organ in Koi has special sensory cells to function as smell receptors.