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Reprinted
with permission from:
Dr. Joanne Norton
Freshwater And Marine Aquarium
magazine
Angelfish Genetics
Photos and Text
by Dr. Joanne Norton
FAMA: October 1982, Vol. 5, #10
Part Six
In the author's
recent articles on Angelfish Genetics,
the discussion has concerned pigment
patterns produced by mutant genes and
also by various combinations of these
genes. All of this information
pertained to angelfish raised with a
14 hour photoperiod. However, the
discovery has been made that
continuous light affects the pattern
of not only silver angelfish but of
some other genotypes as well.
Years ago a local
aquarist, Richard Pohl, told me that
his silver angelfish raised in
continuous light lacked the striped
pattern. In a corner of his fish room
he kept a light bulb turned on day and
night to provide heat for brine shrimp
hatching. Young silver angelfish in
the tanks that were exposed to this
light did not develop stripes, but
those raised in tanks that were in the
dark at night had the usual stripes.
In my recent FAMA
articles on angelfish genetics I
discussed pigment patterns produced by
mutant genes and also by various
combinations of these genes. All of
this information pertained to
angelfish raised with the lights on
about 14 hours per day. However, I
have discovered that continuous light
affects the pattern of not only silver
angelfish as Richard Pohl found, but
of some other genotypes as well. I did
not notice any difference in either
marble or smokey angelfish raised in a
14-hour day compared with those raised
in continuous light. Some of the other
genotypes that I have tested with a
24-hour day are the subject of this
article. Compare the usual pattern of
wild-type (silver) raised in a 14-hour
day (Fig. 1) with a silver
without stripes that was raised in
continuous light (Fig. 2). I
obtained, from an aquarium shop, a
female that genetically was wild-type.
She produced all wild-type offspring
when mated to a wild-type. However,
this female had no body stripes and
had a few small black spots on the
body (Fig. 3)
Fig. 1: Wild type (silver) 14 hours
light.
Fig. 2: Wild type (silver) continuous
light.
Fig. 3: Genetically wild type, this
female's lack
of stripes may have been caused by
exposure to
continuous light during her early
life.
A zebra angelfish
raised in a 14-hour day has three
prominent vertical stripes on the body
(Fig. 4). Single-dose zebras
raised in continuous light for 136
days from the spawning date had
numerous black dots on the body, and
were the same after two months in a
14-hour day (Fig. 5).
Fig. 4: Zebra (one dose of the gene
for zebra)
14 hours light.
Fig. 5: Zebra (one dose of zebra),
continuous light
for 136 days, then 14-hour day for 2
months.
Another spawn of
single dose zebras that were kept in
continuous light for five months and
then a 14-hour day for two months had
some black spots and also some narrow,
vertical, partial stripes (Fig. 6
and Fig. 7).
Fig. 6: Male zebra (one dose of
zebra),
continuous light for five months, then
14-hour
day for 2 months
Fig. 7: Female zebra (one dose of
zebra), continuous
light for five months, then 14-hour
day for 2 months.
The black lace
angelfish, which has one dose of dark,
is similar to silver but
darker-colored (Fig. 8).
Raising a black lace in continuous
light results in a dusky-colored fish
with little or no evidence of stripes
on the body. At 54 days after they
became free-swimming, these black lace
were dusky-colored and had a faint
dark vertical stripe on the rear part
of the body. After being raised for a
total of 63 days in continuous light,
these fish were changed to a 14-hour
day. Eleven months later, they still
were dusky-colored, with faintly
darker vertical stripes sometimes
showing (Fig. 9) and other
times fading completely (Fig. 10).
Fig. 8: Black lace (one dose of dark)
14-hour day.
Fig. 9: Black lace, continuous light
for 63 days
then 14-hour day for 11 months.
Fig. 10: Black lace, continuous light
for 63 days
then 14-hour day for 11 months.
In this case the
dusky, almost stripeless, pattern was
set by only about two months of
continuous light, and this pattern did
not change to the usual black lace
pattern even after 11 months of a
14-hour day. As I shall point out in
the next article, not all patterns are
set by two months of continuous light.
A true black
angelfish, having two doses of dark,
has vertical stripes that can be seen
by shining a strong light on the body
with a flashlight; this is the pattern
that develops if the lights are turned
off at night during the early part of
the fish's life. However, if you raise
true black angelfish in continuous
light, the body will be solid, velvety
black with no stripes (Fig. 11).
Fig. 11: This true black (two doses of
dark) was
raised in continuous light until it
was quarter
body size; it has no stripes. The
photo was taken
a year later, after the fish was kept
in a 14-hour
day during that year.
In the following
cases it would be difficult or
impossible to know the genotype of an
angelfish by its appearance if you
know nothing about its parents or how
it was raised:
(1) A fish having
one dose of stripeless may have one or
a few black blotches, or it may have
none, on the body. If it has no black
blotches, it looks like a wild-type
(silver) that was raised in continuous
light. The fish can be tested by
mating it to a wild-type, raising the
offspring with the light turned off at
night. If the tested fish has one dose
of stripeless, half of its offspring
will lack stripes. If the tested fish
is wild-type that was raised in
continuous light, none of its
offspring will lack stripes unless
both parents carry the recessive gene
for new gold, in which case some golds
will appear in the offspring.
(2) A black lace
(one dose of dark) raised in
continuous light may resemble a
butterfly (one dose of dark and one
dose of stripeless) that was raised
with the lights off at night. The fish
can be tested by mating it with a
wild-type and raising the young with
the lights off at night. If the tested
fish is black lace that was raised in
continuous light, 50% of the offspring
will be black lace and 50% will be
wild-type. If the tested fish is a
butterfly, the offspring will consist
of wild-type, stripeless, black lace,
and butterfly.
(3) A black with no
stripes could be a true black (two
doses of dark) raised in continuous
light. Or it could be a true black
with one dose of stripeless, raised
with the lights either on or off at
night. I have not raised in continuous
light any blacks having one dose of
dark and one dose of new gold, which
have stripes when raised with the
lights off at night. You can test a
black to find out if it has one dose
of stripeless by mating it with a
wild-type; raise the offspring with
the lights off at night. If stripeless
is not present in a true black, this
cross will produce 100% black lace
offspring. If the true black has one
dose of stripeless, you will get black
lace as well as butterfly, which does
not have stripes on the body.
Several years ago
Jack Wattley told me about some discus
without vertical stripes that another
aquarist had reported to him. I asked
Mr. Wattley if those discus had been
raised with the lights on or off at
night. He replied that it was
interesting that I asked, since he
understood that these discus had been
raised in continuous light. I did not
follow up on the matter, but think
long day length should be considered
as a possible cause of no stripes in
discus.
Angelfish Genetics: Part Seven
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