Angelfish (Pomacanthidae) are among the most colorful fish in the Atlantic, Pacific, and Indian Oceans.
Lovers of tropical marine fauna, especially marine aquarists, divers, and snorkelers, particularly enjoy the now independent family of angelfish (Pomacanthidae).
Currently, 91 different species are known. In addition, there are numerous hybrids that can arise from the predominant mode of reproduction, spawning in open water. The unique feature of the entire family is the backward-facing thorn on the underside of the gills, which in some species often has a contrasting color.
This gill spine (H. Debelius calls it the "gill thorn") distinguishes angelfish from the often similar butterflyfish (Chaetodontidae), to whose family angelfish were classified until a few years ago.
Systematics:
Class: Ray-finned fishes (Actinopterygii)
Subclass: True bony fishes (Teleostei)
Superorder: Spiny-finned fishes (Acanthopterygii)
Order: Perciformes
Suborder: True perches (Percoidei)
Family: Angelfishes (Pomacanthidae)
Genera:
* Dwarf angelfish (Centropyge)
* Smoke angelfish (Apolemichthys)
* Velvet angelfish (Chaetodontoplus)
* Lyre angelfish (Genicanthus)
* Angelfish (Holacanthus)
* True angelfish (Pomacanthus)
* Peacock angelfish (Pygoplites)
In the global fish species database "FishBase," all species listed under the family Pomancanthidae are predominantly referred to as angelfishes. However, a more detailed classification of the various genera has also been established. A distinction is made between dwarf angelfish (in German-speaking countries also known as duke angelfish (Centropyge), smoky angelfish (Apolemichthys), velvet angelfish (Chaetodontoplus), lyre angelfish (Genicanthus), angelfish (Holacanthus), and the actual large angelfish (Pomacanthus).
It has been proposed several times to introduce the following systematization for a clearer distinction. Accordingly, the Centropyge species should be called duke angelfish, and the genera Apolemichthys and Chaetodontoplus should be called dwarf angelfish. Helmut Strutz was a strong advocate of this theory. However, differing opinions still exist regarding this classification.
The different lifestyles and, above all, social behavior can thus be classified in more detail. The respective genera live either solitarily, like most species of Apolemichthys and Chaetodontoplus,
in larger groups, like the Centropyge, or in harem groups, like the Genicanthus, Holacanthus, and Pomacanthus, on the other hand, mostly live in pairs. In group and harem formations, one could speak of a patriarchy, because here an adult, dominant female becomes the male and leader of the group. With anemonefish, it's exactly the other way around.
There is another peculiarity with the giant angelfish, Holacanthus and Pomacanthus. As already mentioned, the adults of these genera usually live in pairs and do not tolerate competitors in their territory. For this reason, the juveniles have completely different coloring and are thus not recognized as competitors. This juvenile coloration is a necessary "trick" of nature for peaceful coexistence on the reef. Only as they mature do the animals change color in various phases until they reach adulthood.
Another tip for aquarists: In older literature, size information for fish should always be treated with a certain degree of caution. Strangely, the size of a fish is sometimes given with the tail fin (TL = total length) and sometimes without the tail fin (SL = standard length).
For this reason, and due to a vague idea of how large some species of this family can grow when one sees them swimming cute, small, and colorful at the dealer, many animals were kept in much too small aquariums until recently. Fortunately, this has improved in recent times. Smaller animals, such as those of the Centropyge species, are more commonly kept than larger angelfish.
Among the angelfish, there are dietary specialists that feed almost exclusively on coral polyps and tunicates. However, some of these can be accustomed to alternative foods, usually when they are still young.
The feeding habits of the Centropyge species are particularly interesting.
Once the fish have settled in, if you're unlucky, they'll eventually eat corals. For many aquarists who value their corals above all else, this is sheer horror. They want to get rid of these fish if they can catch them. In aquariums with many Acropora corals, this is sometimes only possible with a fish trap. Once they're finally caught, the search begins for aquarists who want these animals. Surprisingly, once the fish have been moved to another tank, they often don't care for the corals there. No one knows why corals are damaged in one tank and not in another.
However, the reason for this behavior is thought to be whether or not the aquarium has a healthy, well-developed microflora.
In tanks where all rock structures are covered with coralline algae, little green algae can form, or in the worst case, no green algae at all. This means that the fish are likely lacking the plant-based food they need. The animals then obtain this food in the form of zooxanthellae, which live in the cellular tissue of corals. However, it has not been proven that this is the true cause.
Further and different characteristics, specific behaviors, and food preferences are described in more detail in the descriptions of the individual species.
