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Interesting Facts about Butterfly Fish
[Phylum: Chordata] [Class: Actinopterygii] [Order: Perciformes] [Family: Chaetodontidae]
Marine biologists recognise more than 129 different species of butterfly fishes of the family Chaetodontidae, which also includes bannerfish and coralfish.
This section contains fun facts and interesting information about the butterfly fish genus, where to find them, what they eat, and how they reproduce.
Butterfly Fish Habitat and Worldwide Range
The general appearance of this large family of tropical marine fishes is bold and conspicuous.
By and large, you will find them parading around shallow coral reefs in the Atlantic, Pacific, and Indian Oceans.
To the untrained eye, butterflyfish bear a resemblance to the saltwater angelfish (Pomacanthidae) and the Moorish idol (Zanclus cornutus).
However, the absence of the preopercle membrane, and spines around the gills, clearly sets them apart.
There are some weird fish names in existence. But, the common name of this species refers to its illuminating body patterns. The colours and shades range from black, blue, red, yellow, white, and orange.
Butterfly Fish Characteristics
Much like those seen on the wings of many butterflies, the fish has similar eyespots on the flanks, often with dark stripes running across the eyes.
Other distinguishing features are the deep, laterally compressed body shape and the uninterrupted dorsal fin. By and large, the caudal fin is round or truncated (short), but never ends in two prongs (forked)!
Butterfly Fish Size
It would be rare for any of the marine butterflyfish species to grow much bigger than twenty two (22) centimetres long (8 inches). In fact, the average length for most of the genus is closer to twelve (12) centimetres (4 inches).
Fun Fact: The lined butterfly fish (Chaetodon lineolatus) and the saddle butterflyfish (Chaetodon ephippium) are the two largest members in the species, each measuring up to thirty (30) centimetres long (12 inches).
What Do Butterfly Fish Eat?
In general, butterflyfishes are territorial creatures and most active during the daylight hours (diurnal). Even so, it would be unusual to find them swimming around any underwater habitats deeper than eighteen (18) metres (59 feet).
Butterfly marine fish are typical corallivores that feed most on:
- Coral reef polyps (soft-bodied organisms)
- Invertebrate sea anemones
- Microscopic organisms (zooplankton)
They often swim and eat in pairs, usually laying claim to a specific coral head when feeding.
Even so, reef butterflyfish become rather timid during the darkness and seek refuge in coral fissures and crevices.
Pro Tip: Many of the dive sites in southeast Asia offer ideal opportunities to catch sightings of this species as they search for food scraps, especially around artificial reef structures and sunken shipwrecks.
Types of Butterfly Fish Species
Atoll Butterflyfish (Chaetodon mertensii)
Chaetodon mertensii is one of the lesser-known butterflyfishes characterised by its psychedelic colouring and captivating body patterns.
This section contains fun facts and interesting information about the merten's butterflyfish (aka the atoll butterflyfish), including where they live, what they eat, and how they reproduce.
Blackback Butterflyfish (Chaetodon melannotus)
The common names are black-backed butterflyfish and blackback butterflyfish, but they both belong to the butterfly fish scientific name Chaetodontidae.
Like many types of saltwater butterfly fish, they are found throughout the Indo-Pacific region, in Micronesia (including the Line Islands), East Africa, and the Red Sea.
They thrive best around thickets of staghorn corals in nutrient-rich lagoons and outer reef slopes, typically between three (3) metres and their lower depth limit of twenty five (25) metres (80 feet).
Appearance and Behaviour
Blackback butterflyfish have bright yellow body colouring with a large black saddle located on their upper back, but beneath the dorsal fin (hence the common name 'blackback').
They also have a yellow snout and silver white face with a black eye band, a physical feature that's typical in many butterflyfish species.
It's rare for fully grown adults to get much longer than eighteen (18) centimetres (7 inches) in length. They are typical diurnal creatures that are commonly seen swimming in pairs or small groups, particularly during the onset of their breeding seasons.
Conservation Status
Although coral reef degradation presents some long-term threat, the IUCN Red List of Threatened Species assessed the blackback butterflyfish (Chaetodon melannotus) as being of "Least Concern" in 2009 but with a "Decreasing" population trend.
Pro Tip: The PADI® Fish Identification Certification is a great way for scuba divers and snorkelers to learn more about the characteristics of butterfly fish.
Blackwedged Butterflyfish (Chaetodon falcula)
Copperband Butterflyfish (Chelmon rostratus)
Dotted Butterflyfish (Chaetodon semeion)
Eight-Banded Butterflyfish
Foureye Butterflyfish
Lined Butterflyfish (Chaetodon lineolatus)
Ornate Butterflyfish (Chaetodon ornatissimus)
Pennant Coralfish
Raccoon Butterflyfish
Redtail Butterflyfish
Saddle Butterflyfish (Chaetodon ephippium)
Schooling Bannerfish
As the common name suggests, there is a schooling species of bannerfish that enjoys swimming together in large groups around shallow coral reefs.
The blog contains fun facts and interesting information about schooling bannerfish (Heniochus diphreutes), including where they live, what they eat, and how they reproduce.
Speckled Butterflyfish
Spot-naped Butterflyfish (Chaetodon oxycephalus)
Spot-tailed Butterflyfish (Chaetodon ocellicaudus)
Sunburst Butterflyfish
Teardrop Butterflyfish
Threadfin Butterflyfish
Vagabond Butterflyfish
Wiebel's Butterflyfish (Chaetodon wiebeli)
Wrought-Iron Butterflyfish
Yellow-dotted Butterflyfish (Chaetodon selene)
Butterfly Fish Reproduction
Because butterfly fish are broadcast spawners, they release large numbers of buoyant, pelagic eggs into the open water near to the surface.
The eggs float with planktonic organisms in the currents until they hatch, usually within a day of fertilisation taking place.
Following that, the tiny fry enter the postlarval stage of Chaetodontidae and Scatophagidae (also called tholichthys stage). Simply put, large, bony armour plates extend from the head and cover the rest of the body in some of the postlarval fish species until they reach maturity.
Butterflyfish Predators and Threats
Even though butterflyfishes can enjoy a healthy lifespan up to ten (10) years in the wild, the ones kept as marine aquarium pets tend to have shorter lifetimes.
On top of that, they face some significant threats from predatory fish species outside of captivity. For instance, the main hunters are:
Other contributing factors for the decline in a few vulnerable areas include certain types of human behaviour (e.g. coral reef destruction and degradation, overfishing).
The general conservation status of most butterflyfishes is "Least Concern" (LC) according to the information on the International Union for Conservation of Nature (IUCN) website.
Fun Fact: Having a vivid and conspicuous colouration means they are popular fish for aquarium hobbyists to keep as pets.
Related Information and Help Guides
- Atoll Butterflyfish: Fun Facts about Chaetodon mertensii
- Blenny Fish Facts and Species Information with Pictures
- Schooling Bannerfish Habitat and Geographic Distribution
Note: The short video [2:33 minutes] presented by 'Animal Planet' contains even more butterfly fish facts with footage of different species swimming and feeding in their natural habitat.