1022-7954/01/3710- $25.00 © 2001
MAIK “Nauka
/Interperiodica”
1210
Russian Journal of Genetics, Vol. 37, No. 10, 2001, pp. 1210–1211. Translated from Genetika, Vol. 37, No. 10, 2001, pp. 1438–1440.
Original Russian Text Copyright © 2001 by Katassonov, Dementyev, Klimov.
Our earlier studies [1–6] revealed four basic color
types determined by the presence or absence of melan-
ophores and xanthophores in the outer layers of fish
skin. The development of black pigmentation is deter-
mined by digenic system
B
1
,
B
2
. The genotype of fish
with reduced melanophores (orange and white) is
b
1
b
1
b
2
b
2
. Among white and orange fish, carps having a
dirty dark tint of body color occur which substantially
deteriorates commercial value of ornamental fish. In a
histological study, we found that melanophores are not
completely reduced in these carps. A certain amount
number of black pigment cells is preserved in the lower
skin layer and the subcutaneous layer. The appearance
of these cells through the skin produces the impression
of dirty dark body color in orange and white fishes. We
termed this color type as underlying dark color, and
carps possessing this trait were named orange–dark and
white–dark.
Our objective was to study the inheritance of this
trait in order to provide the possibility of purposed pro-
duction of fish with a desired color type.
Fish (mainly, the bloodstock male ornamental carps
from the collection maintained at the Central Experi-
mental Station, All-Russia Research Institute of Fresh-
Water Fisheries) were studied in 1999–2000. The
bloodstock male ornamental carps that were brought
from the Electrogorsk fishery farm (in 1999) and the
Ropsha fishery farm (Federal Genetic and Breeding
Center) (in 2000) were used in some crosses.
We conducted nine crosses of the participation of
bloodstock fish with “pure” or underlying dark color.
The obtained offspring was grown in the ponds of the
Experimental Station (All-Russia Research Institute of
Fresh-Water Fisheries). Segregation ratios by body
color were determined on netting the young of the cur-
rent year. The agreement between the observed and the-
oretically expected segregation ratios was tested using
the
χ
2
test.
In the dissected skin, pigment cells were studied
using a binocular microscope (low magnification).
In most progenies obtained, segregation by body
color had a complex pattern. For the sake of simplicity,
we examined segregation by the studied trait only in
white and orange fish (table).
In the crosses of bloodstock fish of white–dark
color, the color segregation ratio was the closest to the
theoretically expected 15 : 1. If only one of the parents
had the underlying dark color, the segregation ratios
were close to 1 : 1 and 3 : 1. The exception was cross 6,
in which a white–dark female was crossed with a white
male having small black spots dispersed throughout the
body. In the progeny of this cross, the overwhelming
majority of fish had a pure white color. In the cross
between fish of a pure white color, all offspring also had
this type of color.
Taking into consideration the segregation pattern,
we can conclude that the underlying dark color is a
dominant trait in relation to the pure body color. Hence,
we suppose that each gene of digenic system control-
ling the development of melanophores in the skin of
fish (
B
1
,
B
2
) includes three rather than two alleles with
the following order of dominance
B
>
B
' >
b
. Allele
B
'
(which is recessive to allele
B
and dominant over allele
b
)
determines an incomplete reduction of melanophores
and their preservation in the lower skin layer, which
causes the presence of underlying dark color in orange
and white fish.
Generally, the data of the table fit this scheme of
inheritance. Most likely, a small excess of pure-colored
fish, which was found in most progenies, is related to
wrong identification of fish possessing this trait,
because the intensity of underlying dark color varied
Genetics of Color in the Ornamental Carp:
The Inheritance of Underlying Dark Coloration
V. Ja. Katassonov, V. N. Dementyev, and A.V. Klimov
All-Russia Research Institute of Fresh-Water Fisheries, Rybnoe, Moscow oblast, 141821 Russia;
fax: (096) 223-19-05; e-mail: root/amtrv@rex.iasnet.ru
Received February 16, 2001
Abstract
—In ornamental carps from the collection of the Experimental Station, All-Russia Research Institute
of Fresh-Water Fisheries, fish with a dirty dark tint of body color among orange and white fish were found. This
coloration was shown to be due to the presence of black pigment cells in the lower skin layer. In the outer skin
layers these cells were almost entirely absent. This color type was found to be determined by the presence of at
least one of alleles or of digenic system
B
1
,
B
2
, which is responsible for the development of melano-
phores in fish skin. Each of the genes of this digenic system is represented by three alleles with the following
order of dominance:
B
>
B
' >
b
.
B
1
'
B
2
'
SHORT
COMMUNICATIONS
@Phil_Robichaud
@deepthiw
@JoseServera