The shy and enigmatic pygmy angelfish is found on coral and rocky reefs, primarily in the Indo-Pacific region, but a few species can also be found in the western Atlantic. Nigel Marsh takes a closer look at this elusive family of fish.
Bicolor angelfish. Photo by Nigel Marsh.
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It had already been a wonderful dive when I suddenly spotted a group of small yellow fish a few metres away. Always on the lookout for rare and unusual fish, I got very excited when I realised the small yellow fish were Herald’s angelfish. I slowly crept forward, hoping the fish would stay in the open. Unfortunately, the shy fish disappeared into a crevice before I could get within camera range. I decided to wait and see if they would reappear, and today was my lucky day, as one fish emerged, posed perfectly for my camera and then vanished again. I could not have been happier, as after 40 years, I had finally photographed a Herald’s angelfish, a member of a very elusive club—the pygmy angelfish!
Angelfish are some of the most colourful and beautiful of all the reef fishes. The larger members of this family are well known to divers, as they are regularly spotted swimming over reefs. However, the smaller members of the family, known as pygmy angelfish, are shy and cryptic and very quick to hide when a diver gets too close. I have had a soft spot for pygmy angelfish for many years and am always on the lookout to capture images of these elusive fish.
The angelfish family Pomacanthidae contains 88 species found in tropical and subtropical waters around the planet. Sometimes confused with butterflyfish (and damselfish in the case of some pygmy angelfishes), angelfish have several different body characteristics, with the easiest way to tell them apart being the prominent spine on the operculum (gill cover) of angelfish. Most angelfish observed on coral reefs range from 25cm to 50cm in length. However, around half the known species are less than 15cm long, and these are the pygmy angelfish.
Pygmy angelfish
Most pygmy angelfish are members of the genus Centropyge. In this group are 35 related species that are quite small, ranging in size from 6cm to 18cm long. These small fish are benthic omnivores, feeding either on algae or small invertebrates, or both. Pygmy angelfish are usually shy and are found on reefs with plenty of cracks and crevices. They will never venture too far from one of these hiding spots and will flee if a diver or predator swims by.
Pygmy angelfish are found in small groups (unlike most large angelfish, which are seen in male/female pairs), usually one male and up to seven females. The males and females have the same colour pattern and therefore look identical, but the females are often smaller with more rounded fins. The male is the dominant member of the group and fiercely guards his territory from other males, while the females have their own pecking order determined by their size.
When it comes time to reproduce, each female will establish her own little patch, and when the male comes for a visit (usually around dusk), she will release her eggs for him to fertilise. Pygmy angelfish are pelagic spawners, with the eggs drifting with the ocean currents. After the young hatch, they continue to drift for weeks until they settle on a new reef. Young pygmy angelfish have the same colour patterns as their parents, unlike the young of large angelfish that have different colour patterns until they reach adulthood.
Angelfish are protogynous hermaphrodites, meaning they are born female and can change sex to become male. This only happens when the male dies. Then, the dominant female changes sex to take his place. This process takes around 20 days.
It is thought that most pygmy angelfish live for five to seven years. These lovely little fish are found on coral reefs and rocky reefs, in lagoons and on deep drop-offs. They are most numerous and abundant in the Indo-Pacific region, with a few species also seen in the western Atlantic Ocean. However, they are absent from the eastern Pacific and eastern Atlantic Oceans.
The more conspicuous species can be seen flitting around on shallow reefs, but many shy and elusive species hide in caves and crevices and are rarely seen. Over the last few decades, several new species of pygmy angelfish have also been discovered in the twilight zone, at a depth of 60m to 150m. Living in this realm, they are only observed by technical divers.
Common pygmy angelfish
As shy and elusive as most pygmy angelfish are, there are several species that are common and easy to find. One of the most abundant and wide-ranging pygmies is the bicolor angelfish (Centropyge bicolor). This species is very conspicuous on the coral reefs of the Indo-West Pacific, being half yellow and half blue. The bicolor angelfish grows to a length of 15cm, and family groups are found on coral reefs at depths of 1m to 25m. The males are quite territorial and will drive away other males from their territory, which is around 200 sq m. However, they appear to tolerate other fishes, including other pygmy angelfish species, sharing their territory.
Found in the same area and often sharing territory with the bicolor angelfish is the keyhole angelfish (Centropyge tibicen). This species is dark blue to black with a white keyhole pattern on its side and grows to 19cm in length. With its darker colour pattern, the keyhole angelfish is less obvious on coral reefs, where it can be found at depths from 4m to 35m.
The coral beauty angelfish (Centropyge bispinosa) is one of the most wide-ranging members of the family, found from East Africa to French Polynesia. This species grows to 10cm in length and is a bright blue with orange on its side. However, the intensity and shape of this pattern varies from place to place. Coral beauty angelfish are found in a variety of reef habitats between 5m and 50m.
The pearlscale angelfish (Centropyge vrolikii) is another common and wide-ranging species found throughout the Indo-West Pacific region, but it is far more cryptic than the previous species. This fish is a pale grey, with the back half of its body black. It grows to 12cm in length and is found on coral reefs and reef walls at depths of 1m to 25m.
I have had numerous encounters with all the above species of pygmy angelfish. They are seen on the subtropical reefs off my hometown of Brisbane, Australia, but I have also encountered them on trips to the Great Barrier Reef and other destinations throughout the Indo-Pacific region.
Rarer pygmy angelfish
Most pygmy angelfish are rarely seen as they are shy and elusive and like to hide in caves, cracks and crevices. Finding them takes time, patience and being in the right spot at the right time. The following species are some of the rarer pygmies I have encountered. They may not all be rare, but they are all difficult to find and photograph.
There are several uncommon yellow pygmy angelfish that can be easily confused. The first is the lovely lemonpeel angelfish (Centropyge flavissima), which is bright yellow with a light blue ring around the eye and blue highlights on the gill and fins. Growing to 14cm in length, this pretty fish is found across a wide area of the Pacific Ocean. The lemonpeel angelfish is a shy and elusive species found on coral reefs at depths of up to 25m. I have seen this species a few times off Brisbane. However, Fiji is one of the best places to encounter one.
Herald’s angelfish (Centropyge heraldi) is found in the same areas as the lemonpeel angelfish but is a more difficult species to find and observe. It is also bright yellow with a dark grey eye patch and faint orange markings on the head. Herald’s angelfish grow to 12cm in length and are mostly seen on deeper reefs and walls at depths between 8m and 45m. It took me many years to photograph this species before I finally encountered one off Brisbane. I have since found them in Palau and the Philippines.
Another yellow pygmy is Woodhead’s angelfish (Centropyge woodheadi). This is a little-known species from the western South Pacific, and its full range is still not yet known. However, it has been seen off Fiji, Vanuatu and Tonga. The Woodhead’s angelfish grows to 12cm in length and has a yellow body with a black dash along the rear of the dorsal fin, highlighted with a blue trim. This species also has a grey eye patch like the Herald’s angelfish. I have only seen this species in Tonga, and, unfortunately, I was using a wide-angle lens on my camera at the time, so I could not get close enough to take photos of this shy fish.
The midnight angelfish (Centropyge nox) is probably a common species but is easily overlooked due to its all-black colouration, cryptic nature and the fact that it looks more like a damselfish than an angelfish. This species grows to 10cm in length and inhabits coral reefs and walls at depths from 10m to 70m in the western Pacific. I have encountered midnight angelfish in the Philippines and Palau, and they are very difficult to observe and photograph.
Eibl’s angelfish (Centropyge eibli) is a species found only in the eastern Indian Ocean. This pretty angelfish is a light yellowish-grey with a black tail and orange stripes. This species grows to a length of 15cm and is found on coral reefs at depths between 3m and 25m. The Eibl’s angelfish appears to be rare in most locations but locally common in other areas. I have looked for this fish at several destinations in the Indian Ocean, finally finding one at Christmas Island and, more recently, a few at the Similan Islands in Thailand.
A wide-ranging pygmy angelfish seen across the Indian Ocean is the brown angelfish (Centropyge multispinis). This species is dark brown with black stripes and blue margins on its pectoral and anal fins. It grows to 14cm in length and is found in a variety of reef habitats at depths from 1m to 30m. The brown angelfish, with its plain colours, is an easily overlooked species that I have failed to find in the Maldives or the Red Sea. Fortunately, I recently photographed quite a few at the Similan Islands in Thailand.
The flame angelfish (Centropyge loriculus) is one of the prettiest members of this family, and although it is found over a wide stretch of the Pacific Ocean, it appears to be only locally common at a few sites. Bright orange in colour with black bars and blue tips on its dorsal and anal fins, it is hard to miss. This species grows to 15cm in length and seems to like the tops of current-swept reefs at depths up to 20m. I recently encountered twelve flame angelfish on one exposed reef in Palau, but on all the other reefs I explored, I found only one more of these pretty fish.
A very rare member of this family that likes to live in caves is the Cocos-Keeling angelfish (Centropyge colini). This gorgeous little fish grows to 9cm in length and is a pale yellow with a blue back. Found across the Indo-West Pacific, this small angelfish is only occasionally seen, as it is shy and hides in dark recesses at depths between 20m and 100m. On a recent trip to Palau, I found four Cocos-Keeling angelfish on two dives in large dark caves. The fish were extremely shy and very reluctant to have their photo taken.
While this species is sometimes seen in the Cocos-Keeling Islands, these islands and nearby Christmas Island also have several endemic species of pygmy angelfish. When diving in these Australian Indian Ocean Territories, I managed to photograph the cocopeel angelfish (Centropyge cocosensis), which looks very similar to the lemonpeel angelfish, and the yellowhead angelfish (Centropyge joculator), which looks like a cross between lemonpeel angelfish and the bicolor angelfish.
Another rare pygmy angelfish is the barred angelfish (Paracentropyge multifasciatus). This pretty fish is in a different genus from all other pygmy angelfish and looks more like a butterflyfish. Found in the Western Pacific, this lovely fish is white with black bands and a yellow trim to its belly and lower fins. The barred angelfish grows to a length of 12cm and appears to have a similar social life to other pygmy angelfish, with the male having a small harem of females, with both sexes looking similar. These pretty fish are very secretive and are generally found hiding in caves and ledges on reef walls at depths between 10m and 70m. I have encountered this species in Papua New Guinea, Palau and the northern Great Barrier Reef.
Hybrid pygmy angelfish
It is quite common to see several different species of pygmy angelfish milling together on a reef, sharing the same cracks and crevices. Some of these angelfish are so friendly that they interbreed to produce hybrids.
Quite a number of pygmy angelfish seem to like to mix the gene pool, but unfortunately, the only one I have seen a few times on my local reefs off Brisbane is the lemonpeel pearlscale hybrid angelfish (Centropyge flavissima × vrolikii). This species has a colour pattern that is a blend of its two contributing parents, and on some reefs, this hybrid is more common than its parent species.
Why pygmy angelfish interbreed is unknown, although it may be due to the low population numbers of some species. However, a recent study by Yi-Kai (Kai) Tea, a PhD candidate at the University of Sydney’s School of Life and Environmental Sciences, Professors Nathan Lo and Simon Ho, Dr Joseph DiBattista from the Australian Museum, Jean-Paul Hobbs from the University of Queensland and Federico Vitelli from Edith Cowan University, found that angelfish in general produce more hybrids than any other family of reef fishes, with 42 species known to interbreed.
The study found that some angelfish species managed to interbreed with a 12% difference in their mitochondrial DNA. The researchers found this astounding, as the genetic separation between species to typically produce hybrids is usually only 2%. They also found that hybridisation concurred almost anywhere different angelfish species exist side-by-side, while in other reef fish families, hybrids only occurred when similar species closely share habitats.
Pygmy angelfish mimics
There are several species of fish that mimic other fish to keep them safe from predators. Almost all of these mimics copy the colour patterns of venomous fishes to fool predators into thinking they are also venomous. However, for some strange reason, several species of surgeonfish, when juveniles, have copied the shape and colour pattern of pygmy angelfish.
In the Pacific Ocean, the Pacific mimic surgeonfish (Acanthurus pyroferus) has a colour pattern identical to that of the lemonpeel angelfish or the pearlscale angelfish, depending on the location, while in parts of the Indian Ocean, the Indian mimic surgeonfish (Acanthurus tristis) has a colour pattern like the Eibl’s angelfish. These mimics even have a similar body shape and fins and also imitate the swimming style and behaviour of the pygmies, staying close to the reef and darting into cracks and crevices when larger fish are nearby.
The mimics retain these copied colour patterns until they grow larger than the pygmies and develop their defensive blades at the base of their tails. At this stage, they also change shape, with their tails becoming fork-shaped and their snouts elongated, until they start to look like normal surgeonfish.
Why they have chosen to mimic pygmy angelfish is not fully understood, as pygmy angelfish are non-venomous. However, with their shy and elusive behaviour, it is thought that few fish predate on pygmy angelfish as they are just too difficult to catch (and photograph at times), with the mimic surgeonfish benefiting from this sneaky behaviour.
There are still plenty of pygmy angelfish for me to see and photograph, and I can see many years ahead of me looking into countless cracks and crevices for these beautiful and elusive little fish. â–
