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Angelfish color variation is very interesting because the
development of some angelfish pigment patterns depends not only
upon the genetic makeup of the fish but also on the photoperiod
under which the fish is kept during the early months of its
life. Under continuous light, silver angelfish fry develop no
stripes (Norton, 1982c). A zebra lace angelfish having two doses
of zebra and one dose of dark has three black, vertical body
stripes if raised in a 14-hour day; if raised in continuous
light, fish with the same genetic makeup have black spots (the
"cobra" pattern) instead of stripes (Norton, 1982d). This
article is about another spotted pattern, called "leopard" in
the trade, which is dependent on the proper photoperiod during
the early part of the fish's life.
Fig. 1: Leopard angelfish, when purchased.
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| Fig. 1: Leopard angelfish, when purchased. |
Fig. 2: The fish in Figure 1, when adult, now with the smokey pattern.
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| Fig. 2: The fish in Figure 1, when adult, now with the smokey pattern. |
I first saw leopard angelfish in an aquarium shop in March,
1981, and bought one. This fish (Fig. 1) had much lighter
background color than the cobra angelfish, but, like the cobra,
it had black spots on the body. However, as this fish grew, he
changed into a smokey (Fig. 2), in which the rear half of the
body is mottled with black.
Fig. 3: Zebra angelfish, from silver ♀ x leopard ♂.
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| Fig. 3: Zebra angelfish, from silver ♀ x leopard ♂. |
I tested this male for his pigment
pattern genes by crossing him with a silver female. The
offspring all had the zebra pattern of three black, vertical
body stripes (Fig. 3). Then I knew that the leopard male had two
doses of zebra, since zebra is a dominant factor (Norton,
1982b). About half of the offspring developed the smokey pattern
later, so I knew that the leopard male also had one dose of
smokey. Smokey angelfish have a dominant gene; the fry, whether
with or without zebra, are striped at first and then develop the
smokey pattern at a body size of 1 to 1.5 cm (Norton, 1982a,
1982b). A zebra smokey angelfish has a pattern almost identical
to smokey (mottled on the rear half of the body), but with
light-colored spangles in the dorsal and caudal fins (Norton
1982b).
To produce some fish genetically like the leopard male, I
mated this male to a double-dose zebra female. This produced 252
zebra offspring, about half of which developed the smokey
pattern. There were no leopards, even though the smokey zebra
offspring had the same genetic makeup as that of their leopard
father.
Knowing that the dotted pattern of the cobra angelfish
develops in zebra lace fry raised in continuous light, I
suspected that the leopard pattern also might be produced in
smokey zebra fry raised in continuous light. To test this
possibility, I obtained a spawn from a silver female and the
leopard male; the fry were raised in continuous light from one
day before they were free-swimming. None developed the leopard
pattern. About half of them were smokey.
Fig. 4: A zebra angelfish raised in continuous light has black specks, no stripes.
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| Fig. 4: A zebra angelfish raised in continuous light has black specks, no stripes. |
The rest were like the usual pattern in a zebra raised in
continuous light (Norton, 1982c). They had tiny black specks, as
if sprinkled with pepper (Fig. 4) but not the larger dots as in
the leopard pattern. Of course, the flaw in this test was that
these smokeys had only one dose of zebra instead of two that
were present in their leopard father. However, instead of
repeating the continuous light test, this time using a
double-dose zebra female in order to produce some offspring
genetically like the leopard male, I decided to first try
another approach---short day.
Fig. 5: Silver angelfish raised in a 4-hur day.
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| Fig. 5: Silver angelfish raised in a 4-hur day. |
Fig. 6: Another silver angelfish raised in a 4-hour day.
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| Fig. 6: Another silver angelfish raised in a 4-hour day. |
Several years earlier I had raised some silver angelfish in a
4-hour day. These did not develop the usual body stripes of
silver angelfish. Some had a single stripe on the rear part of
the body (Fig. 5) and some had a large blotch instead of a
complete stripe (Fig. 6).
Fig. 7: Leopard pattern. One dose of smokey and two doses of zebra, 4-hour day.
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| Fig. 7: Leopard pattern. One dose of smokey and two doses of zebra, 4-hour day. |
To find out if a 4-hour day would produce the leopard
pattern, I obtained a spawn from a double-dose zebra female and
the leopard male. About half of the offspring would be
genetically like their father, and the other half would be
double-dose zebras, like their mother. The tank containing the
fry was carefully covered with material impervious to light. The
light under the covering was put on a timer to turn on the
lights for four hours per day. The fry were fed newly hatched
brine shrimp during the early part of the light cycle. Being fed
only once a day, these fry grew about half as fast as angelfish
in a 14-hour day and two brine shrimp feedings per day. At last!
Some developed the leopard pattern. The rest, about half of
them, were zebras. At about four months of age, the leopards had
a distinctly spotted pattern on the body (Fig. 7). They looked
like their father did when I brought him home.
Fig. 8: Zebra (above) and leopard (below) not fully developed at 110 days. One dose of smokey and two doses of zebra. 8-hour day, 110 days.
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| Fig. 8: Zebra (above) and leopard (below) not fully developed at 110 days. One dose of smokey and two doses of zebra. 8-hour day, 110 days. |
Fig. 9: Leopard. One dose of smokey and two doses of zebra. 8-hour day. 172 days.
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| Fig. 9: Leopard. One dose of smokey and two doses of zebra. 8-hour day. 172 days. |
Since fry growth rate is very slow in a 4-hour day, I wanted
to find out if leopards could be produced in a 8-hour day. I
obtained another spawn from the double-dose zebra female and the
leopard male, and set the timer for eight hours of light per
day. It was successful, producing 122 leopards and 128 zebras.
At 110 days after the spawning date, the zebras had stripes and
the leopards had broken stripes (Fig. 8). At 172 days, the
zebras still were striped and the leopards had the typical
black-spotted pattern (Fig. 9). These fry grew slowly because I
did not give them a second brine shrimp feeding each day. The
main thing I was trying to find out is whether I would get the
leopard pattern with an 8-hour day. To get faster growth and
have the fry market-ready sooner, more feedings would be
necessary.
Fig. 10: Pattern intermediate between smokey and leopard. One dose of smokey and one dose of zebra. 8-hour day.
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| Fig. 10: Pattern intermediate between smokey and leopard. One dose of smokey and one dose of zebra. 8-hour day. |
Next I wanted to know if a single-dose zebra smokey, raised
in an 8-hour day, would develop the leopard pattern like that of
the double-dose zebra smokey. To test this, I mated a silver
female with the leopard male. The offspring all had one dose of
zebra (from the leopard parent), and half of them also had one
dose of smokey from their father. These were raised in an 8-hour
day. There were 100 zebras and 99 that appeared intermediate
between leopard and smokey, having a rather "moth-eaten"
appearing smokey pattern (Fig. 10). Thus, the single dose zebra
plus smokey did not develop a good leopard pattern.
It is known that a double dose of smokey produces the
chocolate pattern (Norton, 1982a), in which most of the body is
black. Still to be tested is whether the leopard pattern would
develop in an 8-hour chocolate double-dose zebra as it is in a
smokey double-dose zebra. This information would make it
possible to predict the outcome of using leopard parents.
Crossing leopard with leopard, and raising the fry in an 8-hour
day, would produce one-fourth zebras (double-dose zebra, without
smokey), one-half leopards (double-dose zebras plus one dose of
smokey) and one-fourth chocolate zebras (double-dose zebra plus
double-dose smokey). At least it can be predicted that no fewer
than half of the offspring would be leopards. Or fifty-percent
leopards can be obtained from a double-dose zebra female crossed
with a leopard male. Double-dose zebras can be obtained from
zebra parents. The double-dose zebras from this cross can be
picked out because they are runts when young, being about half
as large as their single-dose zebra siblings (Norton, 1982b).
These runts grow to good-sized adults that are prolific
breeders.
The age at which photoperiod-influenced patterns are "set"
and do not change, differs with the pattern (Norton, 1982c).
However, patterns that are set can remain unchanged in adult
fish. I do not know how long leopard angelfish must have a short
daylength so that the pattern will not change to smokey after
the fish are switched to a long day. One commercial fish breeder
told me that he had leopard breeders; if that is true, then the
leopard pattern can be maintained into adulthood.
Also I do not know the limit of a short photoperiod to
produce leopard angelfish. The leopard pattern develops in an
8-hour day, but not in a 14-hour day, which my fish ordinarily
receive. I do not know what would be the result of a nine or ten
hour day, for example.
In summary, the leopard angelfish has two doses of zebra and
one dose of smokey, and it is raised in a short day. The longest
short day tested is eight hours.
Literature Cited
Norton, J. 1982a. Angelfish genetics. Part
one.
Freshwater and Marine Aquarium 5(No. 4):15-18 et seq.
-----.1982b. Angelfish genetics. Part four.
Freshwater and Marine Aquarium 5(No.8):15-17
-----.1982c. Angelfish genetics. Part six.
Freshwater and Marine Aquarium 5(No. 10):38-40
-----.1982d. Angelfish genetics. Part seven.
Freshwater and Marine Aquarium 5(No. 11)40-41
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