The gold marble blushing phenotype is probably best knows as a “koi.” The koi angelfish is a gold marble angelfish with two doses of the stripeless allele. A koi angelfish has one of the following genotypes: Gm/Gm – S/S
Gm/g – S/S The koi angelfish gets its name from the combination of black, white and orange coloration because these same colors are often found in the koi carp, a popular pond fish. A gold marble blushing angelfish will have a white body with black marble-patterned markings. In addition, it will commonly have orange on the crown. The amount of orange coverage can range from being completely absent to covering almost the entire body. The orange coloration has variable expression and is sensitive to environmental conditions and stress. It usually can be seen in very young fry if it is going to express, and will deepen as the angelfish matures. No one has yet definitively identified which environmental factors play the most significant role in achieving good expression of orange. Adult koi on occasion may completely lose their orange. This is generally attributed to stress, but it may be difficult to pinpoint what causes the stress, or to explain why some kois will lose their orange and others will not under stress. Once lost, no one has reported seeing the orange color return. Some people do not refer to a gold marble blushing angelfish as a koi unless it at minimum has an orange crown. Some people will call it a koi regardless of the presence or absence of orange coloration, basing the name on the genotype more rather than the on the presence of orange coloration. (For the sake of simplicity, the terminology “gold marble blushing” and “koi” are used interchangeably on this page.) When the phenotype first became popular, breeders considered a good koi to be one with a full orange crown. Through selective breeding, top breeders have developed lines that exhibit ever increasing percentages of orange coverage on the body, with some koi angelfish having almost 100 percent coverage. |
