Synodontis

Synodontis is the largest genus of mochokid catfishes. It is the biggest genus within the 10 genera and 190 different species in the family Mochokidae. Synodontis has over 131 different species within the genus. Synodontis are also known as squeakers, due to their ability to make stridulatory sounds through their pectoral fin spines when handled or disturbed. Synodontis make a sound that sounds like squeaking by rubbing their spines together. They do this when they have been frightened or when they become angry. Synodontis may also squeak when they are taken out of the water. These catfish are small- to medium-sized fish with many species exhibiting attractive spotted markings. Some species are also known for naturally swimming belly-up, earning the name upside-down catfish. Some of these species are Synodontis contractus and Synodontis nigriventris. While some of these species are known to swim upside down, another species, Synodontis multipunctatus, is a brood parasitic cuckoo catfish,there are two other species Synodontis petricola and Synodontis grandiops are also called brood parasitic cuckoo catfish.
Distribution
Synodontis is a freshwater catfish that is most commonly found throughout Africa, occurring mostly in Central and West Africa. Synodontis is the most widely distributed mochokidae genus, occurring throughout most of the freshwaters of sub-Saharan Africa and the Nile River system. They can live in freshwaters which can be creeks, ponds, streams, lakes, and rivers. Their distribution is similar to that of cichlid fishes, however, unlike cichlids the majority of their diversity occurs in rivers not lakes.
Evolutionary history
Synodontis catfish form a small endemic radiation in Lake Tanganyika, which includes the non-endemic species S. victoriae. This radiation is thought to have evolved relatively recently (~5.5. Million years ago), having diversified within full lacustrine conditions. This is also the case for other endemic Lake Tanganyika lineages such as mastacembelid eels and platythelphusid crabs for example. Lake Tanganyikan Synodontis have also been shown to be Müllerian mimics, and that at least one species (Synodontis multipunctatus) is a brood parasite.
Fossil record
The earliest fossils of Synodontis in East African are from the Early Miocene. Many Synodontis fossils are the spines because they are very sturdy and so they are preserved better. The fossils of spines that are found are used to determine the family or genera of the fish but it cannot determine the species. Synodontis species that have survived and are still living can be identified by the shape of their whisker like organs on their heads called barbels, which relate to touch. The can also be identified by the color of their skin, the skull bones, and the number and length of the teeth.
Ecology
Synodontis species are omnivorous generalists, feeding on a wide spectrum of different foods and are largely unspecialized. Insects, crustaceans, mollusks, annelids, seeds, and algae have been found in the stomachs of different species of Synodontis. They are bottom-feeders and may be detritivores, some species may also be able to adapt to filter feeding. This allows them to cope with seasonal and habitat changes and gives them a better ability to colonize different habitats. Different Synodontis species have somewhat different growth rates but most of them are fairly similar. Females of a species are generally larger than the males. There is a great increase in growth the first year in both male and female and then the growth slows down as they become older. The form and structure of these fish are very different compared to other fish. The size and shape of the mouth are distinct because of its ventral mouth and these fish usually are triangular or cylindrical when looking at it from the side. Not much is known about the reproduction in these fish. It has been determined that July to October is when they spawn and that they swim in pairs during this spawning time. Species of Synodontis have been noted to reproduce with the flooding period of the rainy season.
Relationship to humans
Many Synodontis species are prized ornamental fish in the fishkeeping hobby. While some of the Synodontis species are prized because of their color or behavior, other species are wanted for food. Some of the bigger species in the genus are important food sources for the people in Africa.
Species
There are currently 131 recognized species in this genus: Synodontis accounts for about one-quarter of African catfish species. This genus has more members than any other African teleost genus other than Barbus and Haplochromis.
Newer species are listed with references.
Synodontis acanthomias Boulenger, 1899
Synodontis acanthoperca Friel & Vigliotta, 2006
Synodontis afrofischeri Hilgendorf, 1888 (Fischer's Victoria squeaker)
Synodontis alberti Schilthuis, 1891 (Bigeye squeaker)
Synodontis albolineatus Pellegrin, 1924
Synodontis angelicus Schilthuis, 1891 (Angel squeaker)
Synodontis annectens Boulenger, 1911
Synodontis ansorgii Boulenger, 1911
Synodontis arnoulti Román, 1966
Synodontis aterrimus Poll & Roberts, 1968
Synodontis bastiani Daget, 1948
Synodontis batensoda Rüppell, 1832 (Upsidedown catfish)
Synodontis batesii Boulenger, 1907
Synodontis brichardi Poll, 1959
Synodontis budgetti Boulenger, 1911
Synodontis camelopardalis Poll, 1971
Synodontis carineae Vreven & Ibala Zamba, 2011
Synodontis caudalis Boulenger, 1899
Synodontis caudovittatus Boulenger, 1901
Synodontis centralis Poll, 1971
Synodontis clarias (Linnaeus, 1758) (Mandi)
Synodontis comoensis Daget & Lévêque, 1981
Synodontis congicus Poll, 1971
Synodontis contractus Vinciguerra, 1928 (Bugeye squeaker)
Synodontis courteti Pellegrin, 1906
Synodontis cuangoanus Poll, 1971
Synodontis decorus Boulenger, 1899 (Clown squeaker)
Synodontis dekimpei Paugy, 1987
Synodontis depauwi Boulenger, 1899
Synodontis dhonti Boulenger, 1917
Synodontis dorsomaculatus Poll, 1971
Synodontis eupterus Boulenger, 1901 (Featherfin squeaker)
Synodontis filamentosus Boulenger, 1901
Synodontis flavitaeniatus Boulenger, 1919 (Orangestriped squeaker)
Synodontis frontosus Vaillant, 1895
Synodontis fuelleborni Hilgendorf & Pappenheim, 1903 (Fuelleborn's squeaker)
Synodontis geledensis Günther, 1896 (Geledi squeaker)
Synodontis gobroni Daget, 1954
Synodontis grandiops Wright & Page, 2006
Synodontis granulosus Boulenger, 1900
Synodontis greshoffi Schilthuis, 1891
Synodontis guttatus Günther, 1865
Synodontis haugi Pellegrin, 1906
Synodontis ilebrevis Wright & Page, 2006
Synodontis irsacae Matthes, 1959
Synodontis iturii Steindachner, 1911
Synodontis katangae Poll, 1971
Synodontis khartoumensis Abu Gideiri, 1967
Synodontis koensis Pellegrin, 1933
Synodontis kogonensis Musschoot & Lalèyè, 2008
Synodontis laessoei Norman, 1923
Synodontis leopardinus Pellegrin, 1914 (Leopard squeaker)
Synodontis leopardus Pfeffer, 1896
Synodontis levequei Paugy, 1987
Synodontis longirostris Boulenger, 1902
Synodontis longispinis Pellegrin, 1930
Synodontis lucipinnis Wright & Page, 2006
Synodontis lufirae Poll, 1971
Synodontis macrophthalmus Poll, 1971
Synodontis macrops Greenwood, 1963
Synodontis macropunctatus Wright & Page, 2008
Synodontis macrostigma Boulenger, 1911 (Largespot squeaker)
Synodontis macrostoma Skelton & White, 1990 (Largemouth squeaker)
Synodontis manni De Vos, 2001 (Feather-barbelled squeaker)
Synodontis marmoratus Lönnberg, 1895
Synodontis matthesi Poll, 1971
Synodontis melanopterus Boulenger, 1903
Synodontis melanostictus Boulenger, 1906
Synodontis membranacea (Geoffroy Saint-Hilaire, 1809)
Synodontis multimaculatus Boulenger, 1902
Synodontis multipunctatus Boulenger, 1898 (Cuckoo catfish)
Synodontis nebulosus Peters, 1852 (Cloudy squeaker)
Synodontis ngouniensis De Weirdt, Vreven & Fermon, 2008
Synodontis nigrita Valenciennes, 1840
Synodontis nigriventris David, 1936 (Blotched upsidedown catfish)
Synodontis nigromaculatus Boulenger, 1905 (Blackspotted squeaker)
Synodontis njassae Keilhack, 1908 (Malawi squeaker)
Synodontis notatus Vaillant, 1893 (Onespot squeaker)
Synodontis nummifer Boulenger, 1899
Synodontis obesus Boulenger, 1898
Synodontis ocellifer Boulenger, 1900
Synodontis omias Günther, 1864
Synodontis orientalis Seegers, 2008
Synodontis ornatipinnis Boulenger, 1899
Synodontis ornatissimus Gosse, 1982
Synodontis ouemeensis Musschoot & Lalèyè, 2008
Synodontis pardalis Boulenger, 1908
Synodontis petricola Matthes, 1959 (Cuckoo Catfish)
Synodontis pleurops Boulenger, 1897 (Congo squeaker)
Synodontis polli Gosse, 1982
Synodontis polyodon Vaillant, 1895
Synodontis polystigma Boulenger, 1915
Synodontis pulcher Poll, 1971
Synodontis punctifer Daget, 1965
Synodontis punctulatus Günther, 1889
Synodontis punu Vreven & Milondo, 2009
Synodontis rebeli Holly, 1926
Synodontis resupinatus Boulenger, 1904
Synodontis ricardoae Seegers, 1996 (Ricardo's squeaker)
Synodontis robbianus Smith, 1875
Synodontis robertsi Poll, 1974
Synodontis ruandae Matthes, 1959
Synodontis rufigiensis Bailey, 1968
Synodontis rukwaensis Hilgendorf & Pappenheim, 1903 (Lake Rukwa squeaker)
Synodontis schall (Bloch & Schneider, 1801) (Wahrindi)
Synodontis schoutedeni David, 1936
Synodontis serpentis Whitehead, 1962 (Tana squeaker)
Synodontis serratus Rüppell, 1829
Synodontis smiti Boulenger, 1902
Synodontis soloni Boulenger, 1899
Synodontis sorex Günther, 1864
Synodontis steindachneri Boulenger, 1913
Synodontis tanganyicae Borodin, 1936
Synodontis tessmanni Pappenheim, 1911
Synodontis thamalakanensis Fowler, 1935
Synodontis thysi Poll, 1971
Synodontis tourei Daget, 1962
Synodontis unicolor Boulenger, 1915
Synodontis vaillanti Boulenger, 1897
Synodontis vanderwaali Skelton & White, 1990
Synodontis velifer Norman, 1935
Synodontis vermiculatus Daget, 1954
Synodontis victoriae Boulenger, 1906 (Lake Victoria squeaker)
Synodontis violaceus Pellegrin, 1919
Synodontis voltae Román, 1975
Synodontis waterloti Daget, 1962
Synodontis woleuensis Friel & Sullivan, 2008
Synodontis woosnami Boulenger, 1911 (Upper Zambezi squeaker)
Synodontis xiphias Günther, 1864
Synodontis zambezensis Peters, 1852 (Plain squeaker)
Synodontis zanzibaricus Peters, 1868 (Eastcoast squeaker)
References
Fish of Africa
Catfish genera
Taxa named by Georges Cuvier
Freshwater fish genera