The freshwater hatchetfishes are a family

Family (biology)

In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

, Gasteropelecidae, of ray-finned fish. The common hatchetfish

Common hatchetfish

The common hatchetfish or river hatchetfish, Gasteropelecus sternicla, is a tropical fish belonging to the freshwater hatchetfish family . Originating in South America in the Peruvian and middle Amazon, the Guianas and Venezuela, it grows to about 2.5 inches . The fish gets its name from its...

 is the most popular member among fish keeping hobbyists. The family includes three genera

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

: Carnegiella (4 species), Gasteropelecus (3 species), and Thoracocharax

Thoracocharax

The genus Thoracocharax covers two species of fish in the family of Gasteropelecidae commonly known as "hatchetfish" due to the shape of their bodies. These fish live just under the surface of the water.- List of species :...

(2 species).

Distribution and habitat

Freshwater hatchetfishes originate from Panama

Panama

Panama , officially the Republic of Panama , is the southernmost country of Central America. Situated on the isthmus connecting North and South America, it is bordered by Costa Rica to the northwest, Colombia to the southeast, the Caribbean Sea to the north and the Pacific Ocean to the south. The...

 and South America

South America

South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

 (though they are absent from Chile

Chile

Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

). They tend to be an upper-level fish, often swimming directly below the surface of the water.

Flight

The most obvious trait of the freshwater hatchetfish is their enormously enlarged sternal region. This is accompanied by large pectoral fins and "extraordinarily powerful" associated muscles which "account for up to 1/4 the total body weight". "Quick beats of the pectoral fins" allow hatchetfish to "lift themselves half out of the water and glide along the surface ... Some species can even leave the water for short stretches" Because of this ability to fly and tendency to jump, aquarium

Aquarium

An aquarium is a vivarium consisting of at least one transparent side in which water-dwelling plants or animals are kept. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, marine mammals, turtles, and aquatic plants...

s used to house hatchetfish should have a cover which is tightly sealed to prevent these fish from escaping.

Genera and species

• Genus Carnegiella (Eigenmann
  Eigenmann
  Eigenmann may mean:* Carl H. Eigenmann , ichthyologist, husband of Rosa Eigenmann.* Rosa Smith Eigenmann , ichthyologist, wife of Carl Eigenmann....
  
  , 1909)
  • Blackwinged hatchetfish
    Blackwinged hatchetfish
    The black-winged hatchetfish, Carnegiella marthae, is a freshwater ray-finned fish native to South America.- Physical description :Black-winged hatchetfish has a convex body. It has a very deep ventral profile with its anal fin set back. This species has wing-like pectoral fins that often extend to...
    
    , Carnegiella marthae
  • Pygmy hatchetfish, Carnegiella myersi
    Carnegiella myersi
    The pygmy hatchetfish is a species of hatchetfish native to Peru.-External links:* *...
    
    
  • Dwarf hatchetfish, Carnegiella schereri
  • Marbled hatchetfish
    Marbled hatchetfish
    The Marbled Hatchetfish, Carnegiella strigata, is a small, normally 35 mm in length, freshwater ray-finned fish native to South America. Hatchet shaped, it presents a gold line extending from its eye to its caudal fin while the area below has a brown and cream colored marble-like pattern...
    
    , Carnegiella strigata
• Genus Gasteropelecus (Scopoli, 1777)
  • Silver hatchetfish
    Gasteropelecus levis
    The silver hatchetfish, Gasteropelecus levis, is a member of the The silver hatchetfish, Gasteropelecus levis, is a member of the...
    
    , Gasteropelecus levis
    Gasteropelecus levis
    The silver hatchetfish, Gasteropelecus levis, is a member of the The silver hatchetfish, Gasteropelecus levis, is a member of the...
    
    
  • Spotted hatchetfish, Gasteropelecus maculatus
  • Common hatchetfish
    Common hatchetfish
    The common hatchetfish or river hatchetfish, Gasteropelecus sternicla, is a tropical fish belonging to the freshwater hatchetfish family . Originating in South America in the Peruvian and middle Amazon, the Guianas and Venezuela, it grows to about 2.5 inches . The fish gets its name from its...
    
    , Gasteropelecus sternicla
• Genus Thoracocharax
  Thoracocharax
  The genus Thoracocharax covers two species of fish in the family of Gasteropelecidae commonly known as "hatchetfish" due to the shape of their bodies. These fish live just under the surface of the water.- List of species :...
  
  (Fowler
  Henry Weed Fowler
  Henry Weed Fowler was an American zoologist born in Holmesburg, Pennsylvania.He studied at Stanford University under David Starr Jordan...
  
  , 1907)
  • Greater hatchetfish, Thoracocharax securis
  • Spotfin hatchetfish, Thoracocharax stellatus

Additional reading

• Nelson, Joseph S. (2006). Fishes of the World. John Wiley & Sons, Inc. ISBN 0471250317