A
young Rio Negro angel.
|
| A male
wild-type (silver) angelfish. |
Before 1950, only wild-type (silver) angelfish existed in the
tropical fish trade. Since then, mutations have resulted in a
number of color patterns: black lace, black, ghost, blushing,
smokey, marble, chocolate, zebra, and several different golds. A
search of the scientific literature yielded no reference on the
inheritance of color patterns in angelfish. The first recorded
mutation resulted in the black lace angelfish, which appeared in
about 1953 in Europe. Black lace is similar to wild-type but has
intensified black pigmentation. Innes (1955) discussed this
"partially black" fish. Since all it to ok to get black
angelfish was to obtain a spawn from black lace parents, it is
not surprising that a number of aquarists soon and almost
simultaneously had black angelfish, which were reported by Innes
(July, 1955), Ludwig (June, 1955) and Wolfsheimer (July, 1955).
Ross Socolof told me that he found an angelfish sport without
stripes in 1961, named it "white ghost," and had been selling it
for about two years before the "Conles blushing" angelfish
(named by Lester Boisvert) appeared (Vorderwinkler, 1965).
Blushing angelfish have no body stripes or spots and the
juveniles have red gill areas. Mr. Vorderwinkler stated that
blushing individuals appeared in spawns from the "white ghost"
strain, but did not discuss the genetics of either ghost or
blushing.
About twelve years ago, two more angelfish mutations, marble
(Ash, 1969) and smokey (Ash, 1971) were discovered by Charles
Ash. The marble angelfish has a black-marbled body and its fins
are streaked with black and white. Marble fry, on the first day
that they swim, are darker than wild-type fry. The smokey
angelfish has a splotchy dark pattern on the rear half of the
body, black-tipped dorsal and anal fins, black in much of the
caudal fin, and black on the mouth.
I do not know of any published account on the origin of the
zebra angelfish, which entered the trade in the 1970's. In this
pattern, there are three prominent vertical stripes on the body.
Single-dose zebras also have more (up to 12) light-colored
horizontal bars in the dorsal fin than in wild-type, which has
about 7 or 8. Zebra angelfish are slightly darker-colored than
wild-type at about 3 weeks after they become free swimming.
As far as I know, there have been three kinds of gold angelfish
in the hobby: first, Naja gold: second, Hong Kong gold: and,
third "new gold." These will be discussed in Part 2.
GENETICS OF
THE MUTANT GENES
A
young Rio Negro angel.
|
| A male
black (two doses of dark). |
Dark
It is known (Norton, 1971) that dark is an incomplete dominant
that produces black lace when present in single dose. A double
dose of dark results in a black angelfish.
A
young Rio Negro angel.
|
| A male
black lace (one dose of dark). |
A male black lace (one dose of dark).
By using a flashlight to strongly light the body of a black
angelfish, you can detect faint vertical body stripes. Although
the black lace angelfish is as vigorous as wild-type, the true
black (double dose of dark) is less vigorous and is slow
growing.
A
young Rio Negro angel.
|
| Male
marble (one dose of marble). |
Marble
Marble is an incomplete dominant (Norton, 1971). In single dose,
this gene produces a black and white marble pattern. Most
individuals having two doses of marble have a more
intensely-pigmented and more extensive black pattern, with
smaller and fewer white areas than in a single-dose marble. A
mating of intensely-pigmented marbles produced 100% offspring
like the parents. These fry were slow-growing, taking about
twice as long to reach marketable size as it would take for
single-dose marbles. A dark-patterned marble angelfish that I
suspected had two doses of marble was mated to wild-type; this
produced 412 light-patterned marble offspring, the expected
result if the marble parent had two doses of marble. While
double-dose marble angelfish lack vigor and are slow-growing,
single-dose marbles appear at least as vigorous as wild-type.
Matings of light-patterned marbles with wild-type gave the
expected 1:1 ratio if the marble parent had one dose of marble.
A wild-type female X light-patterned marble male produced 231
light patterned marble and 207 wild-type. A wild-type male gave
46 light-patterned marble and 41 wild-type.
A
young Rio Negro angel.
|
| A male
blushing, adult (two doses of stripeless). |
Stripeless
Stripeless is an incomplete dominant that, in single dose,
produces "ghost," a fish without body stripes; a double dose of
stripeless results in blushing (Norton, 1971), a fish without
body stripes or spots, but with a black vertical bar below the
eye and another black vertical bar at the base of the caudal
fin.
A
young Rio Negro angel.
|
| A juvenile blushing (two doses of stripeless) |
A juvenile blushing angelfish has a greatly decreased number of
iridophores, resulting in translucent rather than reflective
gill plates; therefore the red gill color is visible. In a
mature blushing angelfish, the red gill area disappears because
iridophores develop in the opercular tissue, as well as in
patches on the body and fins. When I removed scales from a
reflective area of a dead mature blushing angelfish, I found
that the reflective tissue is underneath the scales. The mature
blushing male has a more pronounced hump on his head than
usually develops in other types of male angelfish. Also, mature
blushing angelfish, unlike other colors of angelfish, do not
have red color in the iris of the eye.
A
young Rio Negro angel.
|
| Ghost
(one dose of stripeless) with one spot. |
Expression of stripeless in single dose is variable, the body
having no black markings, or with one or more black blotches on
each side. A female with no stripes, but with one large oval
black spot about 2 cm in length on the rear part of the body on
each side (see photo), was tested by mating her to a blushing
male. This produced some each of blushing and stripeless
offspring, the expected result if the one-spot female had one
dose of stripeless.
A
young Rio Negro angel.
|
| Ghost (one dose of stripeless) with two spots. |
Another female with no stripes but with two large oval black
spots on each side of the body was mated to a blushing male.
Again, stripeless and blushing offspring were produced; thus the
two-spot female also had one dose of stripeless.
A
young Rio Negro angel.
|
| Ghost
(one dose of stripeless) with black bar. |
One dose of stripeless does not appear to decrease vigor.
However, the blushing angelfish is less vigorous and
slower-growing than wild-type; thus a double dose of stripeless
decreases vigor. I have had spawns of blushing in which the
incidence of defective swim bladders ("belly sliders") in the
fry was high. Young blushing angelfish are unusually susceptible
to fin infections, and they must have frequent large water
changes to prevent infection of the tips of their dorsal and
anal fins. I have encountered unusually small fry in some spawns
of blushing angelfish. These were not able to eat 36 hour brine
shrimp nauplii (San Francisco), but could eat, for about the
first two days, nauplii that had a 24 hour hatch time and
therefore were smaller than 36 hour nauplii.
A
young Rio Negro angel.
|
| Foreground: Zebra female (one dose of zebra). |
Zebra
No zebra offspring have appeared when neither parent had the
zebra pattern. A wild-type female mated to a zebra male produced
both wild-type and zebra offspring. Two of the F1 zebras were
mated, producing 70 zebras and 26 wild-type, the expected 3:1
ratio if zebra is due to a dominant gene. Single-dose zebras
appear equal in vigor and growth rate to wild-type.
A
young Rio Negro angel.
|
| Male
smokey veil (one dose of smokey) |
Smokey
Crosses of wild-type (with no smokey background) X smokey gave
the expected 1:1 ratio if the smokey parent in each case had one
dose of a dominant gene. The result of these crosses were:
1. wild-type female X smokey male: 53 smokey, 54 wild-type;
2. smokey female X wild-type male: 222 smokey, 231 wild-type;
3. wild-type female x smokey male: 241 smokey, 262 wild-type;
4. wild-type female x smokey male: 426 smokey, 418 wild type;
5. wild-type female x smokey male: 98 smokey, 105 wild type.
Smokey parents produced three kinds of offspring: wild-type,
smokey, and chocolate. Suspecting that chocolate had a double
dose of smokey, I crossed a wild-type female with a chocolate
male; this produced 100% smokey offspring. Thus the gene for
smokey is an incomplete dominant, producing chocolate in double
dose.
A
young Rio Negro angel.
|
| Male
chocolate (two doses of smokey). |
In chocolate, the dark pattern is more extensive than in smokey. Chocolate was named by Adrien (1973) but its genetics
was not discussed. I have noticed no diminished vigor or growth
rate in either smokey or chocolate angelfish, compared with
wild-type.
For approximately two weeks after becoming free swimming, smokey
and chocolate fry appear identical to wild-type. Then, within
two or three days, the anal fin darkens in smokey and chocolate
fry, compared with wild-type. Some of these lose stripes and
develop the smokey (or chocolate) body pattern in about three
more days. Time of development of this pattern varies among
individuals, but all have a posteriorly-mottled body at four to
six weeks after hatching (at 80degress F), usually when the body
diameter is between 1 and 1.5 cm.
PRACTICAL APPLICATIONS
Whatever type of angelfish you want to raise, you will benefit
by obtaining spawns consisting of only one type, not two or more
types. Sorting hundreds or thousands of angelfish is a
time-consuming nuisance for the aquarist. In large-scale
commercial angelfish production involving as many as tens of
thousands of angelfish per week, the time and labor used for
sorting can be very expensive. Sorting often is made even more
difficult and time-consuming by the fact that many angelfish
patterns (including wild-type, black lace, smokey, chocolate and
zebra) fade when the fish are disturbed. In such cases, it is
necessary to sort a few until the patterns begin to fade on
those fish left in the tank, than wait perhaps several hours to
sort more after the patterns reappear.
Most aquarist and even many commercial angelfish producers often
raise angelfish from breeders that produce mixed spawns. For
example, black lace parents are used to produce black lace
angelfish, even though this is not the cross that produces 100%
black lace offspring. There are other cases in which the best
cross to get a certain type requires using parents that are not
like the offspring you want. Following are the crosses that will
produce the greatest percent of the desired type.
Black Lace
Mating black lace x black lace will produce 25% wild-type, 50%
black lace, and 25% black. You may harvest a lower percent of
blacks than this since the fry mortality rate of black angelfish
is high. To obtain 100% black lace, use a wild-type (silver)
female and a true black male. The reason for not crossing a
black female with a wild-type male is that it is common for
black females to produce only a few spawns (Norton, 1971). Many
of the black-colored angelfish in the trade today are not true
black (having two doses of the gene for dark). You can obtain
true blacks by saving the blacks from black lace parents. The
blacks should be raised separately from the rest of the spawn as
soon as you can segregate them because they are slow growing and
will not grow as well if kept with the faster-growing black lace
and wild-type siblings.
Black
True black (two doses of dark) angelfish are not vigorous and,
even though they breed true, they have been replaced largely
with other genetic types of blacks which are more vigorous.
These other kinds of black angelfish will be discussed in a
future article of this series.
Blushing
Since a blushing angelfish has two doses of the gene for
stripeless, the only cross to produce 100% blushing offspring is
blushing x blushing. A word of caution to those aquarist who
raise angelfish with other fishes, such as swordtails or
mollies: This works for most angelfish, but blushing is an
exception. Mollies may pick at the bodies of blushing angelfish,
sometimes killing all of the blushing angelfish in a tank within
a day or two.
Ghost
I do not know of anyone producing ghost (one dose of stripeless)
angelfish commercially. However, 100% ghost angelfish will be
produced by mating blushing with with wild type.
Marble
Double-dose marble angelfish are true-breeding, but since they
are frail and slow-growing, they are not economical to raise.
The hardy and fast-growing single-dose marble is preferable, but
is not true breeding. From single-dose marble parents (which
have less black and more white than in double-dose marble) you
will get 25% dark (double-dose) marble, 50% light (single-dose)
marble, 25% wild-type. This is unsatisfactory not only because
of the sorting required but because the two kinds of marble
angelfish grow at different rates and will not reach marketable
size at the same time. The best mating to produce marble
offspring having no other kind of mutant gene is double-dose
marble x wild-type. (Another commercially valuable marble,
having more than one kind of mutant gene, will be discussed in a
future article.) Double-dose marble angelfish are not common in
the trade, but you can obtain some from a spawn of single-dose
marble parents. You will know that you used single-dose marble
parents if you get wild-type, light-colored marbles, and
dark-colored marbles (having little white), and no other type.
While the fry are small, 1/2" or less total length, segregate
the darkest ones, which also will be the smallest. Most or all
of these will be double-dose marbles, which should be raised by
themselves so that their growth will not be inhibited by their
larger siblings.
Smokey and Chocolate
Smokey angelfish should not be produced by using smokey breeders
because this will give 25% wild-type, 50% smokey, and 25%
chocolate. You will get 100% smokey offspring by mating
wild-type with chocolate. Since chocolate angelfish are seldom
offered for sale, they usually must be obtained from smokey
parents. From then on, you can maintain a chocolate strain,
since chocolate angelfish breed true.
Zebra
Zebra angelfish are not raised commercially, although zebra lace
is common. Zebra lace, which has one dose of zebra and dark,
will be discussed in a future article.
Literature Cited
Adrien, Daniel O. Hybridization in angels.
Buntbarsche Bull. No.
38, pp32-34, 1973
Ash, Charles A. The new marble angel.
The Aquarium 2 (No. 3):4.
1969
Ash, Charles A. The smokey gray veil angel.
The Aquarium 6
(No.6):8-9. 1971
Innes, Wm. T. Introducing perfected black angels.
The Aquarium
24:205-207. 1955
Ludwig, Fred. Tropical Fish Hobbyist, June, 1955
Norton, Joanne. Angelfish-breeding and genetics.
The Aquarium 6 (No. 10):34-41. 1971
Vorderwinkler, William. The Conles blushing angelfish.
Tropical
Fish Hobbyist 13:5-9. 1965
Wolfsheimer, Gene. Black angels. Aquarium Journal 26:177-178.
1955
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