Mouthbrooding, also known as oral incubation and buccal incubation, is the care given by some groups of animals to their offspring by holding them in the mouth of the parent for extended periods of time. Although mouthbrooding is performed by a variety of different animals, such as the
Darwin's frog
Darwin’s frog (''Rhinoderma darwinii''), also called the Southern Darwin's frog, is a species of Chilean/Argentinian frog of the family Rhinodermatidae. It was discovered by Charles Darwin during his voyage on voyage on HMS ''Beagle''. on a ...
, fish are by far the most diverse mouthbrooders. Mouthbrooding has evolved independently in several different families of fish.
Mouthbrooding behaviour
Paternal mouthbrooders are species where the male looks after the eggs. Paternal mouthbrooders include the
arowana
Arowanas are freshwater bony fish of the subfamily Osteoglossinae, also known as bony tongues (the latter name is now often reserved for Arapaiminae). In this family of fish, the head is bony and the elongated body is covered by large, heavy sc ...
, various mouthbrooding bettas and gouramies such as ''
Betta pugnax
The Penang betta (''Betta pugnax'') is a species of gourami native to Southeast Asia and common in swiftly flowing forest streams of the Malay Peninsula, Thailand, Sumatra, and the Riau Islands. In addition to its native range, the species has ...
'', and sea catfish such as ''
Ariopsis felis
The hardhead catfish (''Ariopsis felis'') is a species of sea catfish from the northwest Atlantic and Gulf of Mexico, and similar to the gafftopsail catfish (''Bagre marinus''). It is one of four species in the genus '' Ariopsis''. The common n ...
''. Among
cichlid
Cichlids are fish from the family Cichlidae in the order Cichliformes. Cichlids were traditionally classed in a suborder, the Labroidei, along with the wrasses ( Labridae), in the order Perciformes, but molecular studies have contradicted this ...
s, paternal mouthbrooding is relatively rare, but is found among some of the
tilapiines
The Tilapiini (occasionally Tilapini) are a tribe within the family Cichlidae commonly known as tilapiine cichlids. Formerly this tribe contained many other genera and species, including the economically important ''Oreochromis'' and ''Sarothe ...
, most notably the black-chin tilapia ''
Sarotherodon melanotheron
The blackchin tilapia (''Sarotherodon melanotheron'') is a species of cichlid native to coastal west Africa. It is a paternal mouthbrooder which has been introduced to Asia and North America.
In the Philippines, it is also informally called ''g ...
''.
In the case of the maternal mouthbrooders, the female takes the eggs. Maternal mouthbrooders are found among both African and South American cichlids. African examples are the
haplochromines
__NOTOC__
The haplochromine cichlids are a tribe of cichlids in subfamily Pseudocrenilabrinae called Haplochromini. This group includes the type genus (''Haplochromis'') plus a number of closely related genera such as '' Aulonocara'', '' Astat ...
, such as the
mbuna, ''
Astatotilapia burtoni
''Astatotilapia burtoni'' is a species of fish in the family Cichlidae.
It is found in Lake Tanganyika and its surrounding waterways, including parts of Burundi, Rwanda, Tanzania, and Zambia.
Its natural habitats are rivers, intermittent r ...
'', and the dwarf mouthbrooders ''Pseudocrenilabrus multicolor'', and some of the tilapiines, such as ''
Oreochromis mossambicus
''Oreochromis'' is a large genus of oreochromine cichlids, fishes endemic to Africa and the Middle East. A few species from this genus have been introduced far outside their native range and are important in aquaculture. Many others have ver ...
'' and ''
Oreochromis niloticus
The Nile tilapia (''Oreochromis niloticus'') is a species of tilapia, a cichlid fish native to the northern half of Africa and the Levante area, including Land of Israel, Israel, and Lebanon. Numerous Introduced species, introduced populations ex ...
''. The South American maternal mouthbrooders are all members of the subfamily
Geophaginae (commonly known as "eartheaters" on account of their substrate-sifting feeding mode) such as ''
Gymnogeophagus balzanii'' and ''
Geophagus steindachneri
The redhump eartheater ('Geophagus steindachneri') is a species of eartheater cichlid from freshwater habitats in northwestern South America.Geophagus steindachneri'. FishBase. Agustin, L., Kullander, S., & Torres, A. (2001-2008).
Distribution ...
''.
Biparental mouthbrooding occurs where both parents take some of the eggs. This is relatively rare, but is found among the cichlid genus ''
Xenotilapia
''Xenotilapia'' is a genus of cichlids species endemic to Lake Tanganyika in east Africa.
The International Union for Conservation of Nature (IUCN) has assessed 16 ''Xenotilapia'' species; one of them is considered " Vulnerable" ('' Xenotilapia ...
'', and a single catfish, the
spatula-barbled catfish
The spatula-barbeled catfish (''Phyllonemus typus'') is a species of claroteid catfish endemic to Lake Tanganyika on the border of the Democratic Republic of the Congo, Tanzania, Burundi and Zambia
Zambia (), officially the Republic of ...
(''Phyllonemus typus'').
Typically, after courtship, the male
fertilises the eggs and then collects them in his mouth, holding onto them until they hatch. During this time he cannot feed. Among the maternal mouthbrooding cichlids, it is quite common (e.g., among the mbuna) for the male to fertilise the eggs only once they are in the female's mouth. Some cichlids are able to feed while mouthbrooding the eggs, but invariably they feed less often than they would otherwise do, and after mouthbrooding one batch of eggs, all mouthbrooding fish are underweight and require a period of time to feed and make up for the depletion of their energy reserves.
In all cases, the eggs are protected until they hatch and the fry become free swimming. Only in some cases does the parent extend protection to mobile juveniles. Among the cichlids and arowanas, extension of brood care to the fry is common, and they have behavioural cues to tell fry swimming and feeding away from the parent that danger is approaching and that they should return to their parent's mouth. By caring for their offspring in this way, mouthbrooding fish are able to produce smaller numbers of offspring with a higher chance of survival than species that offer no broodcare.
Aquaculture
Some commercially important fish are mouthbrooders, most notably among the
tilapiines
The Tilapiini (occasionally Tilapini) are a tribe within the family Cichlidae commonly known as tilapiine cichlids. Formerly this tribe contained many other genera and species, including the economically important ''Oreochromis'' and ''Sarothe ...
and
arowana
Arowanas are freshwater bony fish of the subfamily Osteoglossinae, also known as bony tongues (the latter name is now often reserved for Arapaiminae). In this family of fish, the head is bony and the elongated body is covered by large, heavy sc ...
s. Fry harvesting, getting the brooding fish to open its mouth and release the fry, is important if the fry are to be reared artificially. In the case of endangered species, such as
Asian arowana
The Asian arowana (''Scleropages formosus'') comprises several phenotypic varieties of freshwater fish distributed geographically across Southeast Asia. While most consider the different varieties to belong to a single species, work by Pouyaud ...
, harvesting may be supervised by an official to certify that the fish farm is a genuine producer of captive-bred fish.
Brood parasites
Some fish have evolved to exploit the mouthbrooding behaviour of other species. ''
Synodontis multipunctatus'', also known as the cuckoo catfish, combines mouthbrooding with the behavior of a
brood parasite
Brood parasites are animals that rely on others to raise their young. The strategy appears among birds, insects and fish. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were its own ...
: it eats the host mouthbrooder's eggs, while spawning and simultaneously laying and fertilizing its own eggs. The mouthbrooder (typically a cichlid) incubates the cuckoo catfish young, the catfish eggs hatch earlier than the cichlid's eggs, and eat the as-yet unhatched cichlid eggs before being set free.
Families of mouthbrooding fish
Families of fish known to include mouthbrooding species include:
*
Apogonidae
Cardinalfishes are a family, Apogonidae, of ray-finned fishes found in the Atlantic, Indian, and Pacific Oceans; they are chiefly marine, but some species are found in brackish water and a few (notably ''Glossamia'') are found in fresh water. A h ...
(cardinalfish): All paternal mouthbrooders
*
Ariidae
The Ariidae or ariid catfish are a family of catfish that mainly live in marine waters with many freshwater and brackish water species. They are found worldwide in tropical to warm temperate zones. The family includes about 143 species.
Taxonomy ...
(sea catfish): All paternal mouthbrooders
*
Bagridae
The Bagridae are a family of catfish that are native to Africa ('' Bagrus'') and Asia (all other genera) from Japan to Borneo. It includes about 245 species. These fish are commonly known as naked catfishes or bagrid catfishes.
Many large bagrid ...
(Bagrid catfish): the only mouthbrooding species in the family is ''
Bagrus meridionalis
The kampango or kampoyo (''Bagrus meridionalis'') is a critically endangered species of large and predatory bagrid catfish that is endemic to Lake Malawi, Lake Malombe and the upper Shire River in Africa. It prefers areas near rocks in water sha ...
'', which is a biparental mouthbrooder
*
Cichlidae
Cichlids are fish from the family Cichlidae in the order Cichliformes. Cichlids were traditionally classed in a suborder, the Labroidei, along with the wrasses ( Labridae), in the order Perciformes, but molecular studies have contradicted thi ...
(cichlids): Numerous species are mouthbrooders, typically maternal mouthbrooders. Some are paternal mouthbrooders e.g. ''
Sarotherodon melanotheron
The blackchin tilapia (''Sarotherodon melanotheron'') is a species of cichlid native to coastal west Africa. It is a paternal mouthbrooder which has been introduced to Asia and North America.
In the Philippines, it is also informally called ''g ...
'', or biparental mouthbrooders e.g.
eretmodine
Eretmodini is a tribe of African cichlids.
It contains five species of freshwater fish endemic to Lake Tanganyika. They are small fish with reduced swim bladders that are found near the bottom in the turbulent, coastal surf zone.Smith, M.P. (1 ...
cichlids.
*
Channidae
The snakeheads are members of the freshwater perciform fish family Channidae, native to parts of Africa and Asia. These elongated, predatory fish are distinguished by their long dorsal fins, large mouths, and shiny teeth. They breathe air with ...
(snakeheads): Some members of ''
Channa
''Channa'' is a genus of predatory fish in the family Channidae, commonly known as snakeheads, native to freshwater habitats in Asia. This genus contains about 50 scientifically described species. The genus has a wide natural distribution extend ...
'' are paternal mouthbrooders.
*
Liparidae
The Liparidae, commonly known as snailfish or sea snails, are a family of marine scorpaeniform fishes.
Widely distributed from the Arctic to Antarctic Oceans, including the oceans in between, the snailfish family contains more than 30 genera ...
(snailfish): ''
Careproctus ovigerus'' is the only species known to be a mouthbrooder (specifically paternal), but the breeding behavior of many other species in the family is unknown.
*
Opistognathidae
Opistognathidae, the jawfishes, are a family of fishes which have been classified within the order Perciformes, suborder Percoidei but many authorities now classify this family within the clade Ovalentaria and consider that its affinities within ...
(jawfishes): All paternal mouthbrooders
*
Osphronemidae (gouramis): A few genera (notably ''
Betta
''Betta'' is a large genus of small, active, often colorful, freshwater ray-finned fishes, in the gourami family (biology), family (Osphronemidae). The best known ''Betta'' species is ''B. splendens,'' commonly known as the Siamese fighting fi ...
'', by far the largest genus) contain or consist entirely of paternal mouthbrooders. Two species of ''
Sphaerichthys'' are maternal mouthbrooders.
*
Osteoglossidae
Osteoglossidae is a family of large freshwater fish, which includes the arowanas and arapaima. The family contains two subfamilies Arapaiminae and Osteoglossinae, with a total of five living genera.
Osteoglossids are basal teleosts that origin ...
(arowanas): Some members are paternal mouthbrooders
See also
* ''
Amblyopsis
''Amblyopsis'' is a genus of small (up to long) fish in the family Amblyopsidae that are endemic to the central and eastern United States. Like other cavefish, they lack pigmentation and are blind. The most recently described species was in 2014 ...
'' – a genus of cavefish that brood in the gill chambers
*
Gastric-brooding frog
The gastric-brooding frogs or platypus frogs (''Rheobatrachus'') is a genus of extinct ground-dwelling frogs native to Queensland in eastern Australia. The genus consisted of only two species, both of which became extinct in the mid-1980s. The g ...
– an extinct genus of frog that incubated their eggs in the stomach
References
{{Animalbirth
Fish reproduction
Herpetology