|
Reprinted with permission from:
Dr. Joanne
Norton
Freshwater And Marine Aquarium
magazine
Angelfish
Genetics
Photos
and Text by Dr. Joanne Norton
FAMA: November 1982, Vol. 5, #11
Part Seven
In
1974, a tropical fish dealer,
Cleo Poe, bought three "cobra"
angelfish from a Minneapolis
wholesaler. These had fin
markings like those of a zebra
lace (which has one dose of dark
and one or two doses of zebra),
and the body was uniformly
covered with dark dots on a gray
background (Figure 1).
These cobras, which cost $10.00
each (dealer price), were given
to me with the understanding
that I would share the offspring
with Mr. Poe. Unfortunately,
they never reproduced, so I did
not learn anything about the
inheritance of cobra.
Figure 1: Cobra angelfish,
bought from a wholesaler in 1974
Two years
later, Robert Commins wrote an
article, "He's Hoping to Create
an Angel," in a Michigan
newspaper, The Ann Arbor News,
Wednesday, March 24, 1976. This
article was reprinted in the
May-June, 1976, issue of NAC
News, the bulletin of the
National Aquarium Club. I could
tell from the picture in that
article that the tail pattern of
this angelfish, which was raised
and called "cobra" by Ed Sayer,
looked like the tail pattern of
the cobras I had two years
previously. Although the body
pattern of Mr. Sayer's angelfish
was not clear in the photograph,
it appeared to have some dark,
vertical partial stripes,
different from the 1974 cobras,
which had smaller markings in
the form of fairly uniform dots,
with no vertical bars. According
to the Michigan article, Mr.
Sayer's cobras had "black and
gray splashes on a silver
underlay." The article gave no
information on the genetics or
parentage of the fish. The
author stated that Mr. Sayer had
many cobras that came from a
cross of two other varieties, of
which Mr. Sayer said, "Which two
I'd rather not say."
Over the past
eight years I occasionally have
made angelfish crosses in an
attempt to produce some cobras
like the ones I had in 1974. It
was not until this year that I
was successful. After none of my
crosses produced the cobra
pattern, I began to suspect that
day length might be a factor. I
already knew the effect of
continuous light on the patterns
of silver, black lace and zebra
angelfish.
In
Part Six I discussed some
angelfish pigment patterns that
are altered by continuous light.
For example, a silver angelfish
raised by continuous light has
no body stripes, and a black
lace is dusky-colored with
little or no striping. A zebra
angelfish raised with the lights
off at night has three vertical
stripes on the body. In
contrast, a zebra raised in
continuous light has only dots
and sometimes several very
narrow, irregular, vertical dark
markings on the body.
Figure 2: Zebra lace (one
dose of zebra and one dose of
dark) raised in continuous light
for two months, then at a
14-hour day. Photo taken one
year after end of continuous
light exposure.
I obtained
some zebra lace angelfish from a
cross of silver with zebra lace.
These, which has one dose of
dark and one dose of zebra, were
raised in continuous light for
seven months. Instead of
developing the three vertical
body stripes characteristic of
zebra lace raised with the
lights off at night, like the
fish in Figure 2, these
zebra lace had two partial
vertical stripes on a gray
background (Figure 3).
Some of the same spawn were
raised in continuous light for
only two months and then were
switched to a 14-hour day. These
looked like the fish in
Figure 3 at two months, but
gradually developed the 3-stripe
pattern after they were switched
to a 14-hour day. The photo
(Figure 2) was taken one
year after the end of the
2-month exposure to continuous
light. Unlike the modified black
lace pattern that was "set" by
two months of continuous light (Part
Six), the modified zebra
lace pattern was not set by only
two months of continuous light.
Figure 3: Zebra lace (one
dose of zebra and one dose of
dark) raised in continuous light
for seven months. This photo
taken seven months later.
I still did
not have the dotted pattern,
with no vertical bars, of the
1974 cobras. I then decided to
raise in continuous light some
zebra lace with two doses of
zebra. I had a pair of zebra
lace that were double-dose zebra
(each produced 100% zebra
offspring, some with and some
without dark, when tested by
crossing with wild-type). These
zebra lace, each of which had
two doses of zebra and one dose
of dark, were mated, which
produced zebra, black and zebra
lace offspring, all having two
doses of zebra; they were raised
in continuous light. At last!
There were three different
patterns in the offspring: light
ones (double-dose zebra, no
dark), black (double -dose
zebra, double-dose dark), and
dark ones (two doses of zebra
and one dose of dark). The dark
one (Figure 4) looked exactly
like the 1974 cobras, having
dark dots on a gray background,
and no stripes or partial
stripes.
Figure 4: Cobra (two doses
of zebra and one dose of dark,
raised in continuous light),
five months old.
Many organisms
that are affected by day length
will react the same to various
lengths of long day. for
example, and 18-hour day might
produce the same results as a
20-hour day. I have not raised
angelfish in an extremely long
day, with the lights off only a
few hours at night, to see if
this has the same effect as
continuous light on their
patterns.
Figure 5: Each of these
fish has two doses of zebra.
Cobra
angelfish are not true breeding
since they are heterozygous for
dark (one dose of dark). It may
be possible to raise spawns of
100% cobra angelfish. To do
this, you would need to cross a
female double-dose zebra
(Figure 5) with a black
zebra male (Figure 6, two
doses of zebra and two doses of
dark). I suggest using a
black zebra male rather than
female since black males without
zebra can be effective breeders
for numerous spawns, while black
females may spawn only a few
times and then quit reproducing.
The required breeders can be
obtained from any zebra lace
parents, which produce zebra,
zebra lace and black offspring,
and also silver and black lace
if both parents have only one
dose of zebra. The slow-growing
zebras would be the ones to
select, since they are the ones
with two doses of zebra (see
Part Four). The black zebras
also are slow-growing, like
blacks without zebra.
Figure 6: Black zebra (two
doses of dark and two doses of
zebra).
If the black
double-dose zebra proves to be a
poor breeder, which would not
surprise me, then the next best
way to get cobras is from zebra
lace parents. You can get 50%
cobras from zebra lace parents
that are homozygous for zebra
(two doses of zebra and one dose
of dark). There will be some of
this type of zebra lace in
spawns in which both parents are
zebra lace. Again, select the
slow-growing zebra lace, as
these are the ones likely to
have two doses of zebra. A zebra
lace can be tested by mating it
with silver. If it is a
double-dose zebra, then all of
the offspring of this cross will
have the zebra pattern (three
vertical stripes), with or
without dark, so there will be
50% zebra and 50% zebra lace.
The cobra
angelfish is no longer a
mystery; it can be raised by
anyone who knows what parents to
use and that the spawns should
be raised in continuous light. I
have never seen cobra angelfish
in shops or in shows, so I have
the impression that they are
rare in the hobby and trade.
Perhaps, with knowledge now
available on how to produce
them, more of this attractive
angelfish will be seen in the
future. It is important,
however, for anyone who buys
cobra angelfish to realize that
these fish will produce no cobra
offspring if the spawns are
raised with the lights off for a
long period (how long is not yet
known) at night.
Clown Angelfish
|
