Domestic Angelfish

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Domestic Angelfish
 

Leopard
Feb 1985: Vol.8, # 2

Published with permission from BowTie Inc., publisher of FishChannel.com.

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.
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 ♂.

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.

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.
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.

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.
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.

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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