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Dr. Norton's Articles - Part 4

Reprinted with permission from:

Dr. Joanne Norton
Freshwater And Marine Aquarium magazine

Angelfish Genetics
Photos and Text by Dr. Joanne Norton
FAMA: August 1982, Vol. 5, #8

Part Four

Parts One, Two and Three of this series covered the inheritance of the mutant genes affecting color of angelfish. In this article I shall discuss combinations of zebra and dark with other genes.

Zebra is the only gene investigated that looks the same in single and double dose. Hong Kong gold and new gold are recessive genes, producing gold angelfish on in double dose. Smokey in double dose results in chocolate. Dark makes black lace in single dose, black in double dose. Double-dose marble in most cases has more black than single-dose marble. Stripeless in single dose removes the body stripes; in double dose it also decreases iridescence, resulting in blushing.

A pair of zebra angelfish produced 62 wild-type and 158 zebra offspring. Thus, each of the parents had one dose of zebra. A number of zebras were runts while the wild-type offspring appeared more uniform in size. I measured the total length of each of the offspring at 51 days of age; the results are given in Table 1. The percent of small zebras was higher than the percent of small wild-type. For example, 67.2% of the zebras were 27mm or less, while only 37.1% of the wild-type were 27mm or less.

number
of wild type

number
of zebras

total
length
in
mm

17
19
20
21
22
23
24
25
26
27
28
29
30
32
34
35

1
3
2
4
6
6
14
13
9
2

1
2
4
6
11
12
14
15
17
24
20
17
13
1
1

TABLE 1. Sizes of the offspring
of zebra parents

Since vigor is decreased by double doses or dark, marble and stripeless, I suspected that double-dose zebra decreases growth rate, resulting in the higher incidence of runts in the zebra offspring compared with their wild-type siblings. The obvious size difference in the zebras can be seen in the photo of three young zebras, two of which are runts. I selected ten of the small zebras to raise to adults. When these reached breeding age, I selected one male and one female to test to find out whether they had one or two doses of zebra. Each of these, when mated to wild-type, produced 100% zebra offspring. The zebra male produced 695 zebra offspring in two spawns. The zebra female produced a spawn of 385 zebras. Thus, these zebra parents that were runts as juveniles were double-dose zebras that were prolific. They were about average-sized adults, the male being 4" and the female 3 1/8" total length at one year.

Zebra
Figure 1: Two double dose zebra (runts) and one
single dose zebra, age 51 days.

Zebra lace, which has one dose of dark in addition to zebra, is a popular and commercially important type of angelfish. Zebra lace parents produce a very unsatisfactory spawn in which 7 out of 16 have decreased growth rate and/or vigor because they have two doses of one or both of the genes for dark and zebra. The expected ratio in the offspring from zebra lace parents is 3 black zebra (1 or 2 doses of zebra plus 2 doses of dark): 6 zebra lace (1 or 2 doses of zebra plus 1 dose of dark): 3 zebra: 1 black (2 doses of dark): 2 black lace (1 dose of dark): 1 wild-type. Of the 6 zebra lace, 2 would be double-dose zebras and, therefore, slow-growing. One out of 3 of the zebras would be double-dose and, therefore, slow growing. The 1 black and 3 black zebras would also be slow-growing. Obviously, zebra lace angelfish should not be produced commercially by using zebra lace breeders. A much better cross is a double-dose zebra female and a true black (two doses of dark) male, which will produce 100% zebra lace offspring, with no runts. True blacks can be obtained from black lace parents, while double-dose zebras are the runts produced by zebra parents.

An angelfish with one dose of zebra and one dose of smokey looks like a zebra when very young. Then the zebra pattern changes into the smokey pattern at about four to six weeks after hatching. The adult zebra-smokey looks essentially like a smokey but has spangles in the dorsal and caudaul fins along with green on the body.

Figure 2: One dose of smokey and one dose of zebra.

Double-dose zebra with one dose of smokey looks the same as single-dose zebra plus smokey. A male zebra-smokey was found to be double-dose zebra by mating him to a wild-type female. All of the offspring were zebras when young, and about half of these developed the smokey pattern.

An individual with marble and zebra looks very much like a marble angelfish but, at maturity, has spangles in the dorsal and caudal fins as well as green color on the head.

Figure 3: One dose of marble and one dose of zebra.

Combinations of dark plus zebra, dark plus marble, and dark plus new gold were discussed in Part Three. Additional combinations of dark are:

2 doses of dark plus zebra: a black fish with light spangles on the tail. This fish does not grow well and is small as an adult.

Figure 4: Black zebra (zebra plus two doses of dark).

1 dose of dark and 1 dose of stripeless: "butterfly," in which the dusky-colored body is without stripes by may have one or more large dark blotches. Adults have much green color. Addition of new gold to butterfly darkens the color.

Figure 5: Butterfly Butterfly (one dose of dark and one
dose of stripeless).

1 dose of dark and 2 doses of stripeless: "blue," having a dusky-colored body and, when young, red gill areas. The adult had iridescent areas on the fins and body, including the areas over the gills, so the red gills do not show. Adults also have green to turquoise on the head, dorsal fin and ventral fins: thus, the adult is an attractive fish.

Figure 6: Juvenile Blue (one dose of dark and
two doses of stripeless).

Figure 7: Adult male blue (one dose of dark and
two doses of stripeless). Joanne Norton.

2 doses of dark and 2 doses of stripeless: "purple," a dark fish without stripes and with red gills showing in the juvenile. This fish is not vigorous and is difficult to raise.

1 dose of dark and 1 dose of smokey: a blotchy dark fish that is light-colored on the anterior part of the body. The adult has turquoise on the head and green on the upper part of the body.

Figure 8: One dose of dark and one dose of smokey.
Age 3 mo.

Figure 9: One dose of dark and one dose of smokey.
Mature male.

A fish with 1 dose of dark, 1 dose of stripeless and 1 dose of zebra looks similar to a butterfly angelfish but with more dark blotches on the body. Also, an adult with these three genes has light spangles in the dorsal, anal and caudal fins.

Figure 10: Juvenile (quarter body size) with one dose
each of dark, stripeless, and zebra.

Figure 11: Adult male with one dose each of dark,
stripeless, and zebra.

By using the proper types of parents you can obtain 100% of some of the angelfish types. For the types covered in this article, use the following crosses:

To get 100% zebra, cross a double-dose zebra with a wild-type (silver). Do not use single-dose parents, which produce 25% wild-type and 75% zebra in which one-third will be runts.
To get 100% zebra lace, cross a double-dose zebra female with a true black male. Do not use zebra lace parents, which produce many types of offspring, including many runts.
To get 100% butterfly, cross a blushing female with a true black male. Do not use butterfly patents, which produce a ratio of 1 purple: 3 black: 3 butterfly: 3 blue: 2 stripeless: 2 black lace: 1 blushing: 1 wild-type. These would really keep you busy sorting.

It is not possible to produce 100% blue (1 dose of dark and 2 doses of stripeless) unless you are able to raise and get spawns from a purple, which is difficult. It is better to use blue parents, which produce 25% purple, 50% blue and 25% blushing. It is common for many of the purples to die during the first week or two, leaving in the spawn about two-thirds blue and one-third blushing.

Angelfish Genetics: Part Five

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