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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.
Fig. 1: Wild-type (silver) 14 hours light.
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| Fig. 1: Wild-type (silver) 14 hours light. |
Fig. 2: Wild-type (silver) continuous light.
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| Fig. 2: Wild-type (silver) continuous light. |
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.
Fig. 3: Genetically wild type, this female's lack of stripes may have been caused by exposure to continuous light during her early life.
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| Fig. 3: Genetically wild type, this female's lack of stripes may have been caused by exposure to continuous light during her early life. |
Fig. 4: Zebra (one dose of the gene for zebra) 14 hours light.
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| Fig. 4: Zebra (one dose of the gene for zebra) 14 hours light. |
Compare the usual pattern of wild-type
(silver) raised in a 14-hour day (Fig. 1 above) with a silver without
stripes that was raised in continuous light (Fig. 2 above). 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. 5: Zebra (one dose of zebra), continuous light for 136 days, then 14-hour day for 2 months.
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| Fig. 5: Zebra (one dose of zebra), continuous light for 136 days, then 14-hour day for 2 months. |
Fig. 6: Male zebra (one dose of zebra), continuous light for five months, then 14-hour day for 2 months.
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| Fig. 6: Male zebra (one dose of zebra), continuous light for five months, then 14-hour day for 2 months. |
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).
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. 7: Female zebra (one dose of zebra), coninuous light for five months, then 14-hour day for 2 months.
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| Fig. 7: Female zebra (one dose of zebra), coninuous light for five months, then 14-hour day for 2 months. |
Fig 8: Black lace (one dose of dark) 14-hour day..
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| Fig 8: Black lace (one dose of dark) 14-hour day. |
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.
Fig. 9: Black lace, coninuous light for 63 days then 14-hour day for 11 months. Faint vertical stripes show part of the time.
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| Fig. 9: Black lace, coninuous light for 63 days then 14-hour day for 11 months. Faint vertical stripes show part of the time. |
Fig. 10: Black lace, coninuous light for 63 days then 14-hour day for 11 months. No vertical stripes showing when this photo was taken.
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| Fig. 10: Black lace, coninuous light for 63 days then 14-hour day for 11 months. No vertical stripes showing when this photo was taken. |
Eleven months
later, they still were dusky-colored, with faintly darker
vertical stripes sometimes showing (Fig.9) and other times
fading completely (Fig. 10).
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.
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.
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| 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. |
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).
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.
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