Gasteropelecus sterniclaCommon hatchetfish(Also: River hatchetfish)
Geographic Range
Gasteropelecus sternicla is known to naturally occur in the Amazon river basin and most of its tributaries. Most of the scientific expeditions that have collected this particular species have done so in the far north of the Amazon river system (Hems 1983).
Distribution map of the range of G. sternicla from the NEODAT II Project.
- Biogeographic Regions
- neotropical
Habitat
As stated earlier, G. sternicla lives in the Amazon river and most of its tributaries. Here the fish lives near the surface. It frequents well-vegetated areas near shore, but when schooled, will venture out into open water (Hems 1983).
- Terrestrial Biomes
- rainforest
- Aquatic Biomes
- rivers and streams
Physical Description
Female Gasteropelecus sternicla are known to reach a maximum length of about 49 millimeters (mm), while their male counterparts reach a maximum of about 42 mm. They have a compressed body with near circular pectoral and abdominal regions. This area of the its body contains a group of well-developed pectoral muscles that may make up 25% of the its body weight. The pectoral fins are upward-facing and wing-like. The dorsal fin is placed in a small dip in an otherwise straightened back near the caudal peduncle. The caudal fin is rather unremarkable in appearence and of normal size. The ventral fins are smaller than normal and rather insignificant. The anal fin has a long base and ends near the tail base (Hems 1983; Davenport 1994; Alkins-Koo 2000).
- Other Physical Features
- bilateral symmetry
Reproduction
Research has shown that Gasteropelecus sternicla only breed for a short period coinciding with the start of the rainy season. The eggs are laid by the female, then the male will swim near the eggs and release his sperm. It is not known if the female releases all of her eggs at once, or if they are deposited at different times during the breeding season. It is known however, that all of the eggs are developed at the same time in the ovaries. The unusal shape and body cavity size of the species may account for the fact that its brood size is generally smaller than other tropical fishes of its size. Females as small as 33mm, and males as small as 31 mm, were both found to have mature gonads (Alkins-Koo 2000).
Behavior
G. sternicla is not an aggressive fish. The hatchet fish usually swims in large schools with others of its kind in the rivers of South America. This particular fish has quite an interesting way to avoid danger, it has the ability to fly for short distances. G. sternicla will use its large, wing-like pectoral fins,powerful caudal peduncle, and forked caudal fin to taxi at the water's surface. Suddenly they will explode from the water, fins still flapping, and fly above the water's surface for up to 3 to 4 meters! It's not actually flying though, they actually skim the waters surface. Some scientists have labeled this behavior as hydroplaning as opposed to flight (Hems 1983; Davenport 1994).
- Key Behaviors
- natatorial
- motile
Communication and Perception
Food Habits
The hatchet fish has a diet which is composed primarilly of insects and larvae. They only feed near the surface of the water, so many terrestrial insects which they eat have fallen into the water. A large part of their diet consists of many winged insects, a large assortment of aquatic insects, and some zooplankton such as daphnia (Hems 1983).
Economic Importance for Humans: Positive
This species is a popular aquarium fish. It has been in Europe since 1912, and in America since at least the 1930's (Hems 1983).
Economic Importance for Humans: Negative
No adverse relationships with humans known.
Conservation Status
-
- IUCN Red List
- No special status
-
- US Federal List
- No special status
-
- CITES
- No special status
Other Comments
G. sternicla was first described in 1758 by Carl von Linne. Its original name was Clupea sternicla. It seems that Linne grouped this fish with the clupeomorphs, such as the gizzard shad.
Contributors
William Fink (editor), University of Michigan-Ann Arbor.
Ali Shakoor (author), University of Michigan-Ann Arbor.
Glossary
- Neotropical
-
living in the southern part of the New World. In other words, Central and South America.
- bilateral symmetry
-
having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.
- chemical
-
uses smells or other chemicals to communicate
- motile
-
having the capacity to move from one place to another.
- natatorial
-
specialized for swimming
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- rainforest
-
rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.
- tactile
-
uses touch to communicate
References
Alkins-Koo, M. 2000. Reproductive timing of fishes in a tropical intermittent stream. Environmental Biology of Fishes., 57: 49-66.
Davenport, J. 1994. How and why do flying fish fly. Reviews in Fish Biology., 4: 184-214.
Hems, J. 1983. The common hatchet fish, Gasteropelecus sternicla. Aquarist and Pondkeeper., 48(1): 44-45.