Dark Locus: Gold Marble Phenotypes
The allele for gold marble is on the dark locus and is designated with
the symbol Gm.
The non-wild alleles at this locus that appear in gold marble
phenotypes are:
Gold Marble (Gm), Gold (g)

Gold marble (Gm) exhibits co-dominance (blending of traits) with the
wild type allele (+). It is recessive to the black (D) and the marble
(M) alleles and is dominant over the gold (g) allele.
Two distinct phenotypes of gold marble occur: gold marble and silver
gold marble. The table below summarizes how the allele for marble
interacts with other alleles at this locus to form the gold marble
phenotypes.
GOLD MARBLE PHENOTYPES AT THIS LOCUS |
Phenotype Common Name |
Gold marble |
Silver Gold Marble
(Barred Gold Marble) |
Genotype: |
Gm/Gm or Gm/g |
Gm/+ |
Pattern of inheritance: |
Gold marble is dominant to Gold. |
Co-dominant with wild type (blending of traits) |
Gold Marble
Gold marble may be homozygous with two alleles for the gold marble
trait (Gm/Gm) or it may be heterozygous with one gold marble allele
paired with one gold allele (Gm/g).





A gold marble is predominantly pale gold colored with random black
markings. The tail, dorsal and anal fins will typically exhibit some
combination of black and white bands or stripes running the length of
the tail or fin. Occasionally an entire fin or tail may be completely
white or completely black. The ventral fins may both be black, both
white, or one may be black and the other white. The crown is
typically darker than the body, with a dark yellow to orange
coloration.
A heterozygous gold marble (Gm/g) will generally exhibit less area
with black markings than a homozygous gold marble (Gm/Gm). Sometimes
the black markings may only consist of one or two small black spots.
However, the amount of black can very from one fish to another, and
from one strain to another, making it generally difficult to determine
the genotype accurately in most gold marbles.
Silver Gold Marble

A silver gold marble is a heterozygous marble in which one marble
allele is paired with one wild type allele. The genotype is shown as
Gm/+. The gold marble and wild type alleles are co-dominant, and the
silver gold marble shows a blending of the two traits. The coloration
will be more muted, grayish silver instead of gold, with black random
black patches. The stripes of the wild silver type will typically be
present, thus it is also often called a barred gold marble.
Factors that Affect Expression of the Gold Marble Phenotype:
Gold marble is constant in its expression. Environmental
conditions do not change the phenotype. Gold marbles raised
under a variety of environmental conditions including different
lengths of daily light will always show the gold marble phenotype.
The black coloration of the marbling does not fade when the fish is
stressed. In the silver gold marble, however, the stripes will fade
when the fish is stressed or frightened, as do the stripes in a wild
type angelfish, whereas the black color of the marbled markings will
not fade.
Changes in the Phenotype as the Angelfish Matures
The marble pattern and coloration is evident in young fry. Although the black markings are established in very young juvenile
gold marbles, some subtler but distinct changes occur as a juvenile
matures into an adult. The most obvious change is the development of
horizontal striations in the white stripes in the dorsal fin; these
striations have blue iridescent bands. The iridescence shows most
intensely when the angelfish is either exhibiting a territorial
behavior or is preparing to spawn.
Gene Interactions
A number of additional phenotypes can be formed when gold marble
phenotypes are combined with non-wild alleles of other genes. All of
these phenotypes still are predominantly gold marble in appearance.
Probably the most popular phenotype is the gold marble blushing, which
results from the addition of two stripeless alleles (S/S) to gold
marble. When the crown is yellow to orange, gold marble blushing is
commonly called koi.
The table below summarizes phenotypes that can be formed from
combining gold marble phenotypes with non-wild alleles at other loci.
Phenotypes resulting from Gold Marble +
Alleles at other Loci |
Alleles |
Gm/Gm, Gm/g |
Gm/+ |
Z/+, Z/Z |
[1] |
Zebra Gold Marble |
S/+ |
Gold Marble Ghost |
Silver Gold Marble Ghost |
S/S |
Gold Marble Blushing (Koi) |
Silver Gold Marble Blushing (Blue Koi)
 |
S/Z |
Gold Marble |
Clown Gold Marble |
Sm/+ |
Smokey Gold Marble |
Smokey Gold Marble |
Sm/Sm |
Chocolate Gold Marble |
Chocolate Gold Marble |
h/h |
Gold Marble Halfblack |
Silver Gold Marble Halfblack |
a/a |
Albino Gold Marble |
Albino Silver GoldMarble |
p/p |
Gold Marble Pearlscale |
Silver Gold Marble Pearlscale |
V/+ |
Gold Marble Veil Tail |
Silver Gold Marble Veil Tail |
V/V |
Gold Marble Super Veil Tail |
Silver Gold Marble Super Veil Tail |
Table note:
[1] Information was not found to confirm the interaction between gold
marble
and zebra.
Links
to additional information about the gold marble allele
Dr. Joanne Norton, FAMA: September 1988, Vol. 11, #9
Dr. Joanne Norton, FAMA: May 1990, Vol. 13, #5
Dr. Joanne Norton, FAMA: December 1993, Vol. 16, #12
Approved by The Angelfish Society
Standards Committee on February 11, 2007.