The Betta Genes
Betta fish color variation is
based on the color pigmentation in different types
of cells. These color cells are in layers within the
skin. In the bottom-most layer are the xanthophores
which produce a yellow color. The next layer of
pigmented cells are the erythrophores, which produce
the red color. On top of these are the melanophores
which produce the black color. Finally, on the
top-most layer are guanophores (iridophores) which
produce the green and blue iridescent colors. These
different types of cells have groups of traits
associated with them. For example, the erythrophores
(red cells) have the extended red trait (red
covering the whole body and fins), the non-red trait
(the complete absence of red) and the wild-type
trait (erythrophores covering portions of the
pelvic, anal and caudal fins and parts of the body).
These traits are determined by the genes of the
Some of the genetics are characterized, however the
characterization is not very well defined. For most
biosynthetic pathways a group of genes encode for
the enzymes which catalyze a series of reactions to
produce a specific pigment.
If any genes in the pathway were mutated such that
an enzyme no longer worked, the pigment would no
longer be produced. This may be the case for the
non-red trait. However, the extended-red trait is
likely due to an expression of a functional protein
involved in the regulation of the entire pigment
biosynthetic pathway. In other words the pigment
biosynthetic pathway can be turned on or off by
protein "switches" in different parts of the fish.
These "switch" proteins (regulatory proteins) can
either work to "turn on" genes in specific regions
of the fish or can work to "turn off" the genes,
depending on where they are in the fish as would be
seen in a trait like the butterfly trait.
Additionally these regulatory proteins can also be
influenced by external stimulus (water conditions,
feeding or during spawning).
So traits (also known as phenotypes) are what we see
and the genes that make up the traits (also known as
genotypes) contain the information for the proteins
that catalyze the reactions to produce the pigment
we see. It can be very complicated, and when
breeding fish outside of an established
strain--anything can happen!
(Extracted From : A Complete Authoritative Guide
Siamese Fighting fish
by Gene A. Lucas, Ph D. ISBN 0-7938-0120-6 )
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20 September, 2006