Frogfish
Frogfishes are any member of the anglerfish family Antennariidae, of the order Lophiiformes. Antennariids are known as anglerfish in Australia, where the term "frogfish" refers to members of the unrelated family Batrachoididae. Frogfishes are found in almost all tropical and subtropical oceans and seas around the world, the primary exception being the Mediterranean Sea.
Frogfishes are small, short and stocky, and sometimes covered in spinules and other appendages to aid in camouflage. The camouflage aids in protection from predators and enables them to lure prey. Many species can change colour; some are covered with other organisms, such as algae or hydrozoa. In keeping with this camouflage, frogfishes typically move slowly, lying in wait for prey, and then striking extremely rapidly, in as little as 6 milliseconds.
Few traces of frogfishes remain in the fossil record, though Fowlerichthys monodi is known from the Miocene of Algeria, and a number of species are known from the Eocene of Italy.
Etymology
The frogfish family, Antennariidae, has its name derived from Antennarius, its type genus. Antennarius suffixes -ius to antenna, an allusion to first dorsal spine being adapted into a tentacle on the snout used as a lure to attract prey.Taxonomy
Antennariidae was first proposed as a family in 1822 by the Polish zoologist Feliks Paweł Jarocki. The 5th edition of the Fishes of the World recognises 13 genera within the family but no subfamilies. Other authorities recognise two subfamilies, the Antennariinae and the Histiophryninae, while others treat these as two separate families. The Antennariidae is classified within the suborder Antennarioidei within the order Lophiiformes, the anglerfishes. The Antennariidae is regarded, with its sister taxon, the Tetrabrachiidae as the most derived clade within the suborder Antennarioidei.Genera
The following classification is based on Eschmeyer's Catalog of Fishes, based on Maile et al. :Subfamily Antennariinae Jarocki 1822
- Abantennarius Schultz, 1957
- Antennarius Daudin, 1816
- Antennatus Schultz, 1957
- †Eophryne Carnevale & Pietsch, 2009
- Histrio Fischer, 1813
- Nudiantennarius Schultz, 1957
- Brachionichthys Bleeker, 1854
- Brachiopsilus Last & Gledhill, 2009
- Histionotophorus Eastman, 1904
- Orrichthys Carnevale & Pietsch, 2010
- Pezichthys Last & Gledhill, 2009
- Sympterichthys Gill, 1878
- Thymichthys Last & Gledhill, 2009
- Fowlerichthys Barbour, 1941
- Neilpeartia Carnevale et al., 2020
- Histiophryne Gill, 1863
- Lophichthys Boeseman, 1964
- Lophiocharon Whitley, 1933
- Allenichthys Pietsch, 1984
- Echinophryne McCulloch & Waite, 1918
- Kuiterichthys Pietsch, 1984
- Phyllophryne Pietsch, 1984
- Porophryne Arnold, Harcourt & Pietsch, 2014
- Rhycherus Ogilby, 1907
- Tathicarpus Ogilby, 1907
- Dibrachichthys Pietsch, J. W. Johnson & Arnold, 2009
- Tetrabrachium Günther, 1880
The division of the family into multiple subfamilies is a recent treatment, as previously the Brachionichthyinae, the Lophichthyinae, and the Tetrabrachiinae were treated as their own families. Histiophrynidae was described as its own family in 2012. In 2022, these four families were found to be paraphyletic with respect to the former treatment of Antennariidae, and due to this, Rhycherinae and Tathicarpinae were uplifted to their own families. A 2025 phylogenetic study combining Ultra-Conserved Elements s, mitochondrial DNA, and morphological data found even this treatment to be paraphyletic, with Fowlerichthyinae being recognized as a distinct clade. However, to avoid taxonomic oversplitting, it was described as a distinct subfamily instead, and the Brachionichthyidae, Histiophrynidae, Lophichthyidae, Rhycheridae, Tathicarpidae, and Tetrabrachiidae were downgraded to subfamilies within the Antennariidae. The frogfishes were also treated as a single family under an interpretive classification of the Actinopterygii in 2024.
The most basal member of the family is thought to be the Fowlerichthyinae.
Fossil record
Very few fossil remains of frogfishes have been found. The oldest known fossil evidence of frogfishes are isolated otoliths, named Antennarius euglyphus Stinton, 1966 from the Early Eocene-aged London Clay Formation of England. The highest diversity has been found in the northern Italian formation at Monte Bolca, formed from the sedimentation of the Tethys Ocean in the early Eocene, which contains two handfish, a Fibonacci frogfish, and a fanfin frogfish related to Fowlerichthys. Another fossil is known from Late Miocene Algeria, Fowlerichthys monodi, believed to be most closely related to the extant Senegalese frogfish.Range
Frogfishes live in the tropical and subtropical regions of the Atlantic and Pacific, as well as in the Indian Ocean and the Red Sea. Their habitat lies for the most part between the 20 °C isotherms, in areas where the surface level water usually has a temperature of or more. They extend beyond the 20 °C isotherms in the area of the Azores, Madeira and the Canary Islands, along the Atlantic coast of the United States, on the south coast of Australia and the northern tip of New Zealand, coastal Japan, around Durban, South Africa, and at Baja California, Mexico. The greatest diversity of species is in the Indo-Pacific region, with the highest concentration around Indonesia. In the small Lembeh Strait, north-east of Sulawesi, divers have found 9 different species. Frogfish live generally on the ocean floor around coral or rock reefs, at most to deep.A few exceptions to these general limits are known. The brackishwater frogfish is at home in ocean waters as well as brackish and fresh water around river mouths. The sargassum fish lives in clumps of drifting sargassum, which often floats into the deeper ocean and has been known to take the sargassum fish as far north as Norway.
Description
Frogfishes have a stocky appearance, atypical of fish. Ranging from long, their plump, high-backed, unstreamlined body is scaleless and bare, often covered with bumpy, bifurcated spinules. Their short bodies have between 18 and 23 vertebrae and their mouths are upward-pointed with palatal teeth. They are often brightly coloured, white, yellow, red, green, or black or spotted in several colours to blend in with their coral surroundings. Coloration can also vary within one species, making it difficult to differentiate between them.Antennarioidei fishes are characterised by the first dorsal fin being made up of three separate spines on the head, the first being the illicium with the second sometimes being short, although this spine is not ever embedded within the skin. The pterygiophores of the first dorsal spine and the third dorsal spine have highly compressed dorsal expansions. The interhyal has a central backwards directed process that touches the preoperculum.
Rather than typical dorsal fins, the front-most of the three fins is called the illicium or "rod" and is topped with the esca or "lure". The illicium often has striped markings, while the esca takes a different form in each species. Because of the variety of colours even within a single species, the esca and illicium are useful tools to differentiate among different varieties. Some of them resemble fish, some shrimp, some polychaetes, some tubeworms, and some simply a formless lump; one genus, Echinophryne, has no esca at all. Despite very specific mimicry in the esca, examinations of stomach contents do not reveal any specialized predation for example, only worm-eating fish consumed by frogfishes with worm-mimicking esca. If lost, the esca can be regenerated. In many species, the illicium and esca can be withdrawn into a depression between the second and third dorsal fins for protection when they are not needed.
Frogfish have small, round gill openings behind their pectoral fins. With the exception of Butler's frogfish and the rough anglerfish, frogfish use a gas bladder to control their buoyancy.
Mimicry and camouflage
The unusual appearance of the frogfish functions to conceal it from predators and sometimes to mimic a potential meal to lure it in. In the study of animal behavior, this is known as aggressive mimicry. Their unusual shape, colour, and skin textures disguise frogfish. Some resemble stones or coral, while others imitate sponges or sea squirts with dark splotches instead of holes. In 2005, a species was discovered, the striated frogfish, that mimics a sea urchin, while the sargassumfish is coloured to blend in with the surrounding sargassum. Some frogfish are covered with algae or hydrozoa. Their camouflage can be so perfect that sea slugs have been known to crawl over the fish without recognizing them.For the scaleless and unprotected frogfish, camouflage is an important defense against predators. Some species can also inflate themselves, like pufferfish, by sucking in water in a threat display. In aquaria and in nature, frogfish have been observed, when flushed from their hiding spots and clearly visible, to be attacked by clownfish, damselfish, and wrasses, and in aquaria, to be killed.
Many frogfishes can change their colour. The light colours are generally yellows or yellow-browns, while the darker are green, black, or dark red. They usually appear with the lighter color, but the change can last from a few days to several weeks. What triggers the change is unknown.