''Macrognathus'' is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of eel-like

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of ...

of the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Mastacembelidae of the order Synbranchiformes. These fish are distributed throughout most of South and

Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical south-eastern region of Asia, consisting of the regions that are situated south of mainlan ...

. ''Macrognathus'' species feed on small aquatic

insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three ...

larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. ...

e as well as

oligochaete Oligochaeta () is a subclass of animals in the phylum Annelida, which is made up of many types of aquatic and terrestrial worms, including all of the various earthworms. Specifically, oligochaetes comprise the terrestrial megadrile earthworm ...

Appearance and anatomy

Most ''Macrognathus'' species attain in length, but a few surpass this size, with the largest being ''M. aral'' at up to . ''Macrognathus'' are mostly similar to ''

Mastacembelus ''Mastacembelus'' is a genus of many species of spiny eel fish from the family Mastacembelidae. They are native to Africa (c. 45 species) and Asia (c. 15 species). Most are found in rivers and associated systems (even in rapids), but there are ...

''. However, they differ in a more modified

rostrum Rostrum may refer to: * Any kind of a platform for a speaker: **dais **pulpit * Rostrum (anatomy), a beak, or anatomical structure resembling a beak, as in the mouthparts of many sucking insects * Rostrum (ship), a form of bow on naval ships * Ros ...

, which may be slightly to significantly larger and longer than those found in ''Mastacembelus''. This serves not only to find food but also to help gather food.

In the aquarium

A number of species of this genus are popular aquarium fish. These include the lesser spiny eel, ''Macrognathus aculeatus'', the spotfinned spiny eel, ''Macrognathus siamensis'', as well as others.

Species

According to FishBase, there are currently 25 recognized species in this genus. According to

Catalog of Fishes Catalog of Fishes is a comprehensive on-line database and reference work on the scientific names of fish species and genera. It is global in its scope and is hosted by the California Academy of Sciences. It has been compiled and is continuously u ...

, one of these, ''M. malabaricus'', belongs in the genus ''

'' instead of ''Macrognathus'' and another, ''M. taeniagaster'', is considered a junior synonym of ''M. circumcinctus''. * '' Macrognathus aculeatus'' ( Bloch, 1786) (Lesser spiny eel) * '' Macrognathus albus'' * '' Macrognathus aral'' ( Bloch & J. G. Schneider, 1801) (Onestripe spiny eel) * '' Macrognathus aureus''

Britz Britz () is a German locality (''Ortsteil'') within the Berlin borough (''Bezirk'') of Neukölln. History The village of ''Britzig'' was first mentioned in 1273. It was incorporated by the 1920 Greater Berlin Act. It is known for being the site ...

, 2010 * '' Macrognathus caudiocellatus'' ( Boulenger, 1893) * '' Macrognathus circumcinctus'' ( Hora, 1924) * ''

Macrognathus dorsiocellatus ''Macrognathus'' is a genus of eel-like fish of the family Mastacembelidae of the order Synbranchiformes. These fish are distributed throughout most of South and Southeast Asia. ''Macrognathus'' species feed on small aquatic insect larvae as ...

, 2010 * '' Macrognathus fasciatus'' Plamoottil &

Abraham Abraham, ; ar, , , name=, group= (originally Abram) is the common Hebrew patriarch of the Abrahamic religions, including Judaism, Christianity, and Islam. In Judaism, he is the founding father of the special relationship between the Je ...

, 2014Plamoottil, M. & Abraham, N.P. (2014): ''Macrognathus fasciatus'' (Synbranchiformes; Mastacembelidae) - a new fish species from Kerala, India. ''Journal of Experimental Zoology, India, 17 (1): 49-54.'' * '' Macrognathus guentheri'' ( F. Day, 1865) (Malabar spiny eel) * '' Macrognathus keithi'' ( Herre, 1940) * '' Macrognathus lineatomaculatus''

, 2010 * '' Macrognathus maculatus'' ( G. Cuvier, 1832) (Frecklefin eel) * '' Macrognathus malabaricus'' ( Jerdon, 1849) * '' Macrognathus meklongensis'' T. R. Roberts, 1986 * '' Macrognathus morehensis'' Arunkumar & Tombi Singh, 2000 * '' Macrognathus obscurus''

, 2010 * '' Macrognathus pancalus'' F. Hamilton, 1822 (Barred spiny eel) * '' Macrognathus pavo''

, 2010 * '' Macrognathus pentophthalmos'' ( Gronow, 1854) ( extinct?) * '' Macrognathus semiocellatus'' T. R. Roberts, 1986 * '' Macrognathus siamensis'' ( Günther, 1861) (Peacock eel) * '' Macrognathus siangensis'' Arunkumar, 2016 * '' Macrognathus taeniagaster'' ( Fowler, 1935) * '' Macrognathus tapirus'' Kottelat & Widjanarti, 2005 * '' Macrognathus zebrinus'' ( Blyth, 1858) (Zebra spiny eel)

References

Mastacembelidae Fish of Southeast Asia {{Synbranchiformes-stub