Characiformes

(Characins)

Class Actinopterygii

Order Characiformes

Number of families 11

Evolution and systematics

Characiformes are members of the superorder Ostariophysi, which contains nearly three-quarters of all freshwater fishes in the world. Characiformes possess several specialized adaptations, common to most Ostariophysi, which enable them to thrive in freshwater environments. One specialized anatomical feature is the presence of the Weberian apparatus, a linkage of bones called ossicles, derived from the vertebrae immediately following the skull, that connect the inner ear and the swim bladder; this structure improves the hearing ability of the fishes. Another evolved characteristic is the production of Schreckstoff, an alarm pheromone released into the water by an injured fish that triggers an escape response in other members of the species. Certain Characiformes, such as blind cavefish, do not produce these pheromones, as such a substance would not enhance a blind fish's ability to escape predators. Other species do not respond to the presence of the pheromones; for example, many characins preyed on by piranhas produce Schreckstoff, but piranhas do not flee when feeding on these species. Finally, the presence of a moveable upper jaw confers a feeding advantage to Characiformes. In some species, the jaw is protrusible, enabling the fishes to use suction pressure to capture prey.

Lineages of Characiformes date back more than 100 million years. Morphological and genetic evidence suggests that much of the species diversity of this group likely developed prior to the time when Africa and South America split into separate continents. The classification of the Characiformes into families has proven complex and controversial. The taxonomic relationships have been revised considerably in the last 30 years, and the classifications continue to change as new evidence becomes available. Although some taxonomists consider there to be up to 16 distinct families, most recognize 11 families: Alestiidae, Anostomidae, Characidae, Citharinidae, Ctenoluciidae, Curimatidae, Erythrinidae, Gasteropelecidae, Hemiodontidae, Hepsetidae, and Lebiasinidae. These families encompass species that are diverse in life form and behavior, with examples including the blind cavefish and predatory piranhas, as well as popular aquarium species such as tetras.

Physical characteristics

Most species of Characiformes are small fishes, although size and shape vary widely throughout the order. The smallest member of the order is the Bolivian pygmy blue characin (Xenurobrycon polyancistrus), which attains a maximum size of around 0.5 in (1.4 cm); the largest species, the giant tigerfish (Hydrocynus goliath) grows to 4.3 ft (1.33 m).

Most Characiformes are brightly colored and often silvery, but some are also brilliant shades of red or blue. Characiformes vary widely in body form. Some species have long and slender bodies, while others, such as hatchetfishes, are deep-bodied and laterally compressed. The body is covered in scales, and the lateral line is often decurved or may be incomplete in some species. Most species have an adipose fin, a short fin between the dorsal and caudal fins. Pelvic fins generally have five to twelve rays, and the anal fin may be short to moderately long, with 45 rays or fewer. Characiformes lack sensory barbels, but they typically have large eyes to heighten visual acuity.

Distribution

Characiformes are found in fresh waters of Texas and Mexico in North America and are widely distributed in Central America, South America, and Africa. Over 1,300 species, 252 genera, and 10 families inhabit South America. At least 176 species in 23 genera and 4 families occur throughout Africa.

Habitat

As a dominant group of freshwater fishes, Characiformes inhabit all types of fresh waters, including weedy river edges, stagnant ponds, rushing streams, and even underground caves. Certain species also possess morphological adaptations, including the ability to breath air or swollen lips that facilitate gas exchange in the upper portion of the water column, that enable them to move into shallow waters of floodplains and flooded forests.

Behavior

The diversity of species represented by the Characiformes necessitates a diversity of behaviors. Many species travel in schools under certain conditions. Some species, such as members of the Ctenoluciidae, form schools as juveniles but become solitary as adults. Other species, including members of the Curimatidae, piranhas, and tetras, travel in large aggregations during all life stages. However, certain species, such as the blind cavefish, rarely gather in groups, and do not form organized aggregations. Although many of the smaller species of Characiformes live their whole lives in a limited geographic area, some species undertake extensive seasonal or spawning migrations.

Courtship behaviors and migrations are associated with spawning in some members of the Characiformes. These unique courtship behaviors often involve fin displays to attract mates as well as elaborate swimming patterns to lure the mate to the spawning site. In addition to complex courtship rituals, some species possess morphological adaptations to attract mates. Males of certain species may utilize sensory cues, including pheromones and visual lures, to gain the attention of females.

Feeding ecology and diet

As reflected by their diversity of body shapes, Characiformes exhibit remarkable feeding specializations and exploit all available trophic modes. Many predatory species, particularly those of the Characidae, have well-developed teeth that enable them to feed on other fish. Some species, such as tiger-fishes, solitarily stalk their prey: others, such as piranhas, engage in voracious group predation. Other carnivorous species

pick or suck invertebrates from the substrate. In contrast, some Characiformes are strictly herbivorous, feeding on plants, fruits, or seeds. Other species filter plankton or are detritivores that feed on mud, algae, and ooze. Among the most remarkable feeding adaptations observed in freshwater fishes, certain Characiformes survive by eating the scales or pieces of fins from other fishes.

Many Characiformes are small-bodied and, thus, fall prey to larger fish species. In fact, predatory piranhas may indiscriminately attack a variety of food items, including smaller characins. Humans are the major predator of some characins. Small species are harvested as bait for fisheries and as trade items for the aquarium industry. A variety of the larger species, particularly tigerfishes, pacus, and piranhas, sustain important local fisheries in South America and Africa.

Reproductive biology

Most Characiformes broadcast their eggs and devote little parental care to their young. The eggs are often scattered among aquatic plants, and the vegetative cover confers some protection to young by providing shelter from predators. In a few species, including members of the Characidae, the male inseminates the female, and she may retain the sperm cells in her ovary for a period of days to months. However, fertilization does not take place until the eggs and sperm are shed into the water column at the same time.

Certain Characiformes exhibit an assortment of more specialized breeding behaviors. Members of the Erythrinidae construct nests for their eggs, and the African pike characins of the family Hepsetidae deposit eggs in a bubble-like nest of floating foam. To avoid egg predation, female splash tetras (Copella arnoldi) jump out of the water and lay their eggs on the underside of overhanging vegetation or rocks. The males follow, fertilize the eggs, and remain in the area to splash water onto the eggs until they hatch. Members of another species, Brycon petrosus, crawl onto the banks of rivers to lay their eggs.

Conservation status

The IUCN Red List includes 7 Characiformes. Six are listed as Data Deficient, and one, the naked characin (Gymnocharacinus bergii), is listed as Endangered. Although international conservation concerns have not been recognized for other

species, many Characiformes are harvested for the aquarium trade, an industry that is monitored and regulated only in certain countries or localities.

Significance to humans

Many Characiformes, including tetras, hatchetfishes, and pencilfishes, are popular aquarium fishes. Others are important as a food resource for humans. Although some species are traded commercially, many are relied upon to meet the subsistence food needs of communities living along tropical rivers. Examples include members of the Citharinidae (dorados) and Serrasalminae (tambaqui and pacus). In addition, some Characiformes, such as tigerfishes, are popular recreational targets that attract anglers from around the world.

Species accounts

List of Species

Giant tigerfish

Hydrocynus goliath

family

Alestiidae

taxonomy

Hydrocynus goliath Boulenger, 1898, Kinshasa and Umangi, Upper Congo.

other common names

German: Wolfsalmler.

physical characteristics

The largest characin, reaching a maximum reported fork length of 4.3 ft (1.33 m) and weight of 110 lb (50 kg). The fish has an elongate, fully scaled body, with a high dorsal fin and deeply forked caudal fin. The body appears silvery, but the back is a darker gray. The fins are often orange or red, and the fish may become brightly colored during the breeding season. The sharp canine teeth are placed alternately on the upper and lower jaws.

distribution

Africa in the Congo River basin, Lualaba River, Lake Upemba, and Lake Tanganyika.

habitat

Large rivers and nearshore areas of lakes.

behavior

Tigerfish aggregate with similar-sized individuals of the same

species, sometimes in schools. Smaller fish occur in large aggregations; large fishes gather with few members in the group. This species migrates in rivers to find appropriate spawning sites.

feeding ecology and diet

Adults are voracious predators that consume a wide variety of smaller fish. Larvae eat zooplankton, but they quickly move to larger prey as they grow. Juveniles and subadults are vulnerable to crocodiles, otters, and a great variety of predatory fishes and fish-eating birds. Humans are the only known predators of aduts.

reproductive biology

Spawning takes place during the summer along the shores of lakes and flooded banks of large rivers. Females disperse hundreds of thousands of eggs into flooded vegetation, where they hatch and develop with no parental care.

conservation status

Not listed by the IUCN.

significance to humans

This species is known internationally as a sport fish and attracts anglers from around the world. It also is sought in local commercial and subsistence fisheries in several African countries, including Tanzania and Zambia.

Striped headstander

Anostomus anostomus

family

Anostomidae

taxonomy

Anostomus anostomus Linnaeus, 1758, South America.

other common names

English: Striped anostomus; German: Prachtkopfsteher; Spanish: Anostomus rayados, lisa; Portuguese: Anostomo.

physical characteristics

Maximum total length 6.3 in (16 cm). Has elongated body with head that tapers to pointed nose, and small upward-facing mouth. Three dark longitudinal stripes start at front of body and extend to tail area; stripes widen as the fish ages. Area between the stripes is gold or mustard color. All fins have red bases; a red spot is apparent on the dorsal fin.

distribution

South America in inland streams and rivers of the Amazon, Orinoco, and Essequibo River basins.

habitat

Mainly weeds, rocks, and woody debris of tropical rivers.

behavior

Often nips at fins of other fishes under aquarium conditions. Swim in slow-moving schools, generally with their heads down, although may tilt the head backward at times while feeding.

feeding ecology and diet

Feeds on worms, crustaceans, insects, and plant material.

reproductive biology

Scatters eggs and fertilizes them in the water column. Few additional details are known.

conservation status

Not listed by the IUCN.

significance to humans

Popular aquarium fish.

Blind cavefish

Astyanax mexicanus jordani

family

Characidae

taxonomy

Astyanax mexicanus jordani Hubbs and Innes, 1936, San Luis Potosí, Mexico.

other common names

English: Blind cave characin, blind cave tetra; German: Blinder Höhlensalmler; Spanish: Sardina ciega; Portuguese: Peixecaverna, Peixe-cego.

physical characteristics

Maximum length 3.5 in (8.9 cm). The species evolved in the darkness of caves. Perhaps because of the absence of light in the environment, the body lacks pigments; instead, it is peachcolored with a silvery sheen. Has a complete lateral line along the body. Fins are colorless and transparent. Another characteristic attributed to the dark environment are vestigial eyes; the eye depressions are covered by skin and other tissue.

distribution

Mexico.

habitat

Subterranean lakes, streams, and pools of underground caves.

behavior

Despite a lack of vision, this species exhibits exceptional navigation abilities. The lateral line is highly sensitive to vibrations, which allows the fish to find food and avoid obstacles as they swim. A solitary species, there is little interaction between individuals.

feeding ecology and diet

General, omnivorous feeders that primarily consume benthic invertebrates and algae. Use their excellent sense of smell to locate food items.

reproductive biology

Spawns by broadcasting eggs. The male and female swim alongside each other near the surface of the water, with their ventral surfaces pressed together; the female scatters eggs, which are then fertilized by the male. The eggs fall to the bottom and hatch in two to three days. The larvae have normal eyes when they hatch, but these become enclosed in tissue after a few weeks.

conservation status

Not listed by the IUCN.

significance to humans

Commonly kept in aquaria, but not as popular as most other characins. Studies of this species have provided useful insights into the evolution of eyes and sight, which can also help improve scientific understanding of human vision.

Bleeding-heart tetra

Hyphessobrycon erythrostigma

family

Characidae

taxonomy

Hyphessobrycon erythrostigma Fowler, 1943, Peru-Brazil border.

other common names

English: Tetra perez; German: Fahnen-Kirschflecksalmler, Perez Salmler; Spanish: Mojarita, punto rojo.

physical characteristics

Standard length 2.4 in (6.1 cm). Deep-bodied fishes that are orange to brown in color on the back and belly. The scales and fins are reddish pink, with a red spot behind the gill cover along the deeply colored lateral line. Dark spots are prominent on the dorsal fin, and the long rays of the dorsal fin are highly arched in males. The anal fin is elongate, stretching from midbody to near the caudal fin. This fin is white in males, a feature that distinguishes them from females, in which the fin is transparent gray.

distribution

Upper Amazon basin of South America.

habitat

Occur in the bottom portion of the water column in freshwater tropical habitats, preferring temperatures of approximately 73–82°F (23–28°C). Individuals often live in vegetation and woody debris.

behavior

Schooling fishes; little is known of their activities, social behavior, or reproductive behavior in nature.

feeding ecology and diet

Omnivore; primarily consumes insects and crustaceans. Because of its small size, succumbs to predation by a variety of larger fishes.

reproductive biology

Females deposit 20–30 eggs in vegetation during each mating act. The eggs incubate for approximately 48 hours in aquaria; fry emerge in three days.

conservation status

Not listed by the IUCN.

significance to humans

Popular aquarium fish that are valued for their bright colors.

Silver dollar

Myleus pacu

family

Characidae

taxonomy

Myleus pacu Jardine and Schomburgk, 1841, Guyana.

other common names

English: Pacu, pacupeba; German: Brauner Mühlsteinsalmler; Portuguese: Pacu dente; Creole: Koumarou-nwé, pakou.

physical characteristics

Maximum length 8 in (20 cm). This species is deep-bodied with a small head and a broad mottled reddish brown body. A row of scutes occurs along the edge of the belly, and the body scales are small. Two rows of teeth are found on the upper jaw; the front row is incisor-like, the back row contains molars.

distribution

South America in Guyana, French Guiana, Brazil, Suriname, and Bolivia.

habitat

Inhabits streams and main stems of rivers.

behavior

Gregarious and rarely aggressive. During the rainy season, large groups migrate to small creeks to reproduce.

feeding ecology and diet

Although their powerful dentition can cause serious bites, silver dollars are herbivores that feed primarily on aquatic plants (often of the family Podostemaceae). Occasionally, they also consume seeds and fruits, which they crush with their large molars. Predators include larger carnivorous fishes, caimans,

otters, river dolphins, and a wide variety of fish-eating birds. Some fish are also taken by humans.

reproductive biology

Reproduce by external fertilization. Females and males swim through the water together; females broadcast eggs into the water column, where they are fertilized by males. No parental care.

conservation status

Not listed by the IUCN.

significance to humans

Common aquarium fishes throughout the world. Also provide an important food source for many communities living near streams inhabited by pacus.

Cardinal tetra

Paracheirodon axelrodi

family

Characidae

taxonomy

Paracheirodon axelrodi Schultz, 1956, Rio Negro, Brazil.

other common names

English: Red neon, neon tetra, scarlet characin; German: Kardinaltetra, Roter Neon.

physical characteristics

Maximum standard length 1 in (2.5 cm). One of the most colorful of the characoids. Although the dorsal portion is gray, the sides are marked with an iridescent turquoise-blue stripe and the lower flanks are bright red. The dorsal fins exhibit a peculiar blue-green iridescence.

distribution

Upper Rio Orinoco and upper Rio Negro of South America.

habitat

This species inhabits a wide variety of habitats. It is often found in shaded or vegetated areas of small, slow-moving, clear, and blackwater creeks. During the rainy season, the fish move into headwaters and flooded forests of rivers. At times of low water, it lives along the margins of lakes or becomes concentrated in creeks and backwaters.

behavior

Often aggregates in shoals of 12–30 individuals in middle portions of the water column. Individuals move onto the floodplain during the rainy season. They are considered "annual fishes," spawning during the spring floods and often perishing due to starvation when foraging habitats retract during the subsequent low-water season.

feeding ecology and diet

Feeds mainly on worms and small crustaceans. Due to its small size, indiscriminately consumed by many larger piscivores, including piranhas.

reproductive biology

Spawns on floodplains of rivers as water levels rise during the rainy season. Females bear 300–500 large eggs; these are broadcast into the water column and fertilized by males. In captivity, eggs hatch in 24–30 hours; fry become freeswimming after three to four days.

conservation status

Not listed by the IUCN. However, this species accounts for 80% of the total catch of ornamental species in some areas, such as the state of Amazonas in Brazil, and this high level of extraction to support the aquarium trade has resulted in local regulations that restrict harvests during the spawning season.

significance to humans

One of the most popular aquarium fishes throughout the world, its commercial harvest for the aquarium trade also supports the economic and social structure of many human communities along the rivers it inhabits in South America.

False rummynose tetra

Petitella georgiae

family

Characidae

taxonomy

Petitella georgiae Gery and Boutiere, 1964, Rio Huallago, Peru.

other common names

English: False rednose tetra, false rummy-nosed tetra; German: Rotmaulsalmler; Finnish: Punapää tetra; Polish: Czerwonoglówka.

physical characteristics

Maximum size 1.5 in (3.9 cm). These fish appear iridescent and shiny in water. The body is silver to olive-brown, with a gold stripe extending from the head to the base of the tail. The

head and the iris of the eye are bright red. The tail is deeply forked and striped, with three black and four white bands. All fins other than the caudal fin are transparent.

distribution

South America in the upper Rio Amazonas basin in Peru, as well as in the Purus, Negro, and Madeira basins in Brazil.

habitat

Swift-moving headwater streams, often preferring the cover of vegetation if available.

behavior

A schooling species; other behavioral features have not been described.

feeding ecology and diet

Feeds on benthic algae, plants, and crustaceans in the plankton and benthos. Its small size makes it susceptible to predation by many larger species of fish as well as water snakes and many different fish-eating birds.

reproductive biology

Reproduces by scattering eggs; females broadcast eggs into the water column, and these eggs are fertilized by the males. Mating activity typically occurs near vegetation in the evening.

conservation status

Not listed by the IUCN.

significance to humans

An important aquarium species.

Pirapitinga

Piaractus brachypomus

family

Characidae

taxonomy

Piaractus brachypomus Cuvier, 1818, Brazil.

other common names

English: Cachama, freshwater pompano, pacu, red pacu, redbellied pacu; German: Gamitana-Scheibensalmler, Riesenpacu; Spanish: Cachama, cachama blanca, morocoto, paco; Portuguese: Caranha, pirapitinga.

physical characteristics

Total length 34.6 in (88 cm). Deep-bodied; appears silvery gray on back and sides, but areas under the throat, along the belly, and at the edges of the pelvic and anal fins are red. Unlike in other Characiformes, the adipose fin contains rays in adults.

distribution

Amazon and Orinoco River basins in South America. Feral individuals have been caught in 16 states throughout the United States, likely as a result of releases from personal aquariums or fish farms.

habitat

Pelagic; occurs in streams and tributaries to main river channels, also in ponds and oxbow lakes.

behavior

Young live in flooded savanna vegetation until about two years old, then move into flooded forests with adults. Feeds during rainy seasons. During low water and just before the start of the second rainy season of the year, adults move upstream in schools to spawn.

feeding ecology and diet

Primarily herbivorous, although it possesses powerful teeth that could inflict severe bites. Feeds mostly on plants and detritus, but may also consume nuts, fruits, seeds, and sometimes insects. Juveniles are vulnerable to larger predatory fishes, notably giant pimelodid catfishes, caimans, otters, and a variety of fish-eating birds. Adults have few predators because of their large size but can be preyed upon by jaguars.

reproductive biology

Spawns as waters begin to rise during the second rainy season. Do not feed during spawning but live off fat stored during the wet season. Eggs are scattered and fertilized in the water column. Males and females mature around seven years of age.

conservation status

Not listed by the IUCN.

significance to humans

One of the most important commercial species in the Amazon basin. Popular food fishes, they are taken in wild fisheries in their native range and raised in fish farms in North and South America. Also popular in aquaria.

Red-bellied piranha

Pygocentrus nattereri

family

Characidae

taxonomy

Pygocentrus nattereri Kner, 1858, Brazil.

other common names

English: Red piranha, redbelly piranha; German: Diamantpiranha, Schulterfleck-Piranha; Natterers Sägesalmler; Spanish: Caribe boca de locha, palometa, paña; Portuguese: Piranha caju; piranha-quexicuda.

physical characteristics

Average length of adult 6–8 in (15.2–20.3 cm), but can grow up to 12 in (30.5 cm). Male and female red piranhas are alike externally, with body height about one-half body length. The stocky bodies have reddish bellies, though overall coloration varies depending on location and age. Sides often pale brown to slightly olive; back bluish gray to brownish; throat belly areas bright red. Forked caudal fin usually gray. Pectoral, pelvic, and anal fins typically bright red. Powerful jaws with triangular, interlocking sharp teeth.

distribution

Widely distributed in South America and in basins of the Amazon, Paraguay-Paraña, and Essequibo Rivers, as well as coastal rivers of northeast Brazil.

habitat

Creeks and interconnected ponds; prefers areas with dense vegetation.

behavior

Diel activity varies by age; adults forage mainly at dusk and dawn, medium-sized individuals are most active at dawn, late afternoon, and night. Smaller fishes feed during the day. Exhibits a "lurking, then dashing" sequence of behaviors during the day. Hierarchical structure often exists in small schools.

feeding ecology and diet

Feeds communally, with groups of 20–30 individuals waiting in vegetation to ambush prey. Prey are attacked in a feeding frenzy, further induced by the presence of blood in the water. Highly predaceous carnivores, but also scavenge for food and consume insects, snails, worms, plants, and fins of other fishes. Can feed continuously and maintain a voracious bite by replacing teeth on alternate sides of the jaw. Preyed upon by other fishes (including large pimelodid catfishes), crocodilians, fisheating birds, and large mammals (including jaguars).

reproductive biology

Spawns through external fertilization. After elaborate courtship display involving swimming in circles, the female deposits layers of eggs on plants in the water, and the male fertilizes them. The male guards and fans the egg masses until they hatch in 9 to 10 days. Annual reproductive success varies, but is dependent upon the degree to which the savanna is flooded.

conservation status

Not listed by the IUCN.

significance to humans

This species is kept as an aquarium fish. This activity is illegal in some states of the United States to prevent irresponsible hobbyists from releasing the species into the wild, where it may multiply and prey upon indigenous fish species. These fish can also inflict serious bites, although they are not as aggressive as once believed, and they are unlikely to attack humans unless the human is bleeding or in water near congregations of other prey species. The species is commonly caught and eaten by river dwellers throughout its extensive range. Large numbers are also caught for use as trot-line bait for large catfishes.

Striped African darter

Nannocharax fasciatus

family

Citharinidae

taxonomy

Nannocharax fasciatus Guenther, 1867, Gabon.

other common names

English: African darter tetra; German: Afrikanischer Bodensalmler.

physical characteristics

Maximum length 2.6 in (6.6 cm). These fish have a short, blunted snout and a thin, elongate body. The body is golden brown on the back, with a dark lateral line midbody, below which is light brown to white. The pigmentation is marked by seven to eleven dark brown transverse bands across the back along the length of the body. The fins are also marked with spots forming transverse bands; a large dark spot is on the anal and adipose fins. The tip of the dorsal fin is red in adults. An elongate pectoral fin extends to the origin of the pelvic fins.

distribution

Throughout equatorial West Africa.

habitat

Clear, swift-moving waters in forested regions; often found over sandy substrates or in similar open areas.

behavior

These fishes live near the water bottom, often in contact with the substrate. They swim with their heads up at an angle of 45° and use long pectoral fins for support while searching for food along the bottom. They rest for longer periods on their pectoral, pelvic, and caudal fins.

feeding ecology and diet

Consumes small invertebrates, including insect larvae, worms, ostracods, and zooplankton near the substrate. Because of their small size, likely consumed by a variety of larger predators.

reproductive biology

Reproduces externally; females scatter eggs in the water column, where they are fertilized by males. Eggs are released in partial batches during several spawning events. There is no parental care.

conservation status

Not listed by the IUCN.

significance to humans

Sometimes kept as aquarium fishes and traded commercially as part of the ornamental fish industry.

Golden pike characin

Boulengerella lucius

family

Ctenoluciidae

taxonomy

Boulengerella lucius Cuvier, 1816, Brazil.

other common names

English: Cuvier's pike characin; German: Cuviers Hechtsalmler; Portuguese: Pirapacu.

physical characteristics

Standard length 16.5 in (42 cm). Elongated, slender fishes resembling North American pikes. Dorsal fin is located toward the back of the body; the anal fin is short. Fishes are metallic green on the back, lighter on sides, and silvery on belly. A small dark spot on caudal fin helps distinguish this species from others in the genus. The jaw terminates in a long fleshy filament and contains numerous teeth.

distribution

Inland waters of the Amazon, Rio Negro, and Rio Orinoco River basins in South America.

habitat

Pelagic; inhabits open waters of large rivers.

behavior

Migrates upriver to spawn during the rainy season.

feeding ecology and diet

Predatory; eats many species of smaller fishes available in open water areas. Predators have not been specified.

reproductive biology

Breeds by external fertilization of eggs. Females release eggs into the water column, where they are fertilized by males. Eggs are demersal, meaning they sink to the bottom.

conservation status

Not listed by the IUCN.

significance to humans

Exploited by humans as a subsistence and commercial food fish; also exported as part of the aquarium trade.

Flagtail prochilodus

Semaprochilodus taeniurus

family

Curimatidae

taxonomy

Semaprochilodus taeniurus Valenciennes, 1817, Amazon River.

other common names

English: Silver prochilodus; German: Nachtsalmler, Schwanzstreifensalmler; Finnish: Juovahuulitetra; Portuguese: Jaraqui, jaraqui escama fina.

physical characteristics

Standard length 9.4 in (24 cm). Like other members of this family, has many small teeth on the jaws and a mouth with enlarged fleshy lips that can be turned outward to form a rasping or suction disk. The lips are often lined with fine papillae, thus the name "flannel mouths." Deep-bodied; dark gray on the back fading to silvery hues on the flanks. Dorsal, anal, and adipose fins are dark gray; pectoral and pelvic fins are nearly clear. Edges of the dorsal and anal fins appear yellow. The caudal fin is most striking, yellow with prominent black horizontal stripes.

distribution

Central portion of the Amazon River basin in Brazil.

habitat

Main channels of streams and rivers, as well as floodplain lakes.

behavior

Undertakes annual migrations for spawning, feeding, and dispersal. At the beginning of the flood season, schools of mature fish migrate downstream from tributaries to the Amazon River to spawn. Migration occurs during the day; spawning takes place at night. After spawning, small groups move into flooded forests of their home tributaries to feed. As soon as the water levels begin to fall, adults undertake a complex dispersal migration. They move back into the main channel of the Amazon and migrate upstream, before dispersing into tributaries other than those in which they lived the year before.

feeding ecology and diet

Primarily consumes plants, algae, and other detritus. It can use its lips as suction cups to eat detritus attached to trees and other submerged vegetation in the flooded forest. Large quantities of mud are often reported in the stomach. Although the fishes are moderate in size, they are preyed upon by larger predatory fishes, such as catfishes.

reproductive biology

Spawning may occur in shallow water along the course of large rivers, sometimes below barriers such as waterfalls. Males emit loud, grunting noises to attract females to the spawning areas. Females scatter a single batch of small eggs into welloxygenated waters. The eggs and fry are carried passively downstream and eventually onto the floodplain, where they begin feeding. After two years, these offspring spawn for the first time.

conservation status

Not listed by the IUCN.

significance to humans

Popular worldwide as an aquarium species. As one of the most common species in the Amazon basin, it is an important food fish for local villages and towns. It is also traded commercially to areas outside the Amazon basin.

Trahira

Hoplias malabaricus

family

Erythrinidae

taxonomy

Hoplias malabaricus Bloch, 1794, South America.

other common names

English: Haimara, tararira, tararura, wolffish, wolf characin; French: Patagaye; German: Kleiner Trahira, Tigersalmler; Spanish: Perro de aqua, tararira; Portuguese: Dorme-dorme, lobó, traira, trairitinga; Palikur: Iigl.

physical characteristics

Standard length 19 in (48.5 cm). Elongated, cylindrical body with short anal fin and large scales. Adipose fin is absent. Bodies of young have reddish brown back and yellowish belly, red bands across the head, and green band along the sides. Adults are mottled dull green and brown.

distribution

Inland waters of most river basins from Costa Rica to Argentina.

habitat

Lives in diverse habitats, ranging from clear streams to slow, turbid waters. Tolerates stagnant conditions in irrigation ditches, drainage channels, and floodplain ponds. Utilizes atmospheric oxygen, enabling it to inhabit low-oxygen habitats, including small brooks or ponds.

behavior

Sedentary species, often remains in a relatively confined geographic area for life. It rests during the day and becomes active at night. These fish may form schools, typically in low numbers. They are ambush predators, waiting quietly under cover until suitable prey items approach.

feeding ecology and diet

Adults are voracious predators that feed on a wide variety of fish and shrimp. Juveniles eat crustacean and insect larvae, shrimp, and other small invertebrates. Trahiras are preyed upon by larger fishes, including piranhas and catfishes, as well as crocodilians, fish-eating birds, and otters.

reproductive biology

Spawns over a protracted reproductive period, with multiple spawnings and size classes distributed uniformly throughout the year. Eggs are adhesive and placed in nests made in nearshore vegetation of shallow, slow watercourses. Male provides a high level of parental care.

conservation status

Not listed by the IUCN.

significance to humans

Supports important commercial fisheries in many countries of South America. Although displayed in some aquaria, not very popular as an aquarium species.

River hatchetfish

Gasteropelecus sternicla

family

Gasteropelecidae

taxonomy

Gasteropelecus sternicla Linnaeus, 1758, Suriname.

other common names

English: Common hatchetfish, silver hatchetfish; French: Poisson hachette argenté; German: Silberbeilbauchfisch; Spanish: Pechito, pechito plateado de raya negra; Portuguese: Borboleta, sapopema, voador.

physical characteristics

Standard length 1.5 in (3.8 cm), but adults in aquaria may reach 2.4 in (6.5 cm). Females are larger than males. Deep, highly compressed body; belly profile creates a semicircular arc containing sternum and strong chest muscles. Pectoral fins are long and located high on the body near the head. Yellow to silver in color, with dark stripe running along the length of the body; fins are transparent.

distribution

South America in the upper Amazon basin, the Guyanas, and Venezuela.

habitat

Pelagic; lives near surface of slow waters in creeks and swamps. Often inhabits vegetated areas.

behavior

Typically gregarious; lives in groups near surface of water. May be aggressive or calm. To avoid predators and capture insect prey, swims very fast to raise its body out of the water, then flies above the surface using its long pectoral fins. Unlike other "flying fish" that rely on gliding, it rapidly beats its pectoral fins to remain airborne for distances up to 10 feet (3 m).

feeding ecology and diet

Feeds on worms, crustaceans, and insects from the surface of the water, but also captures aerial insects. Predators are not specified in current literature, although likely eaten by a variety of larger fishes.

reproductive biology

Spawns after a lengthy courtship. The female scatters eggs in the water or onto floating plants, where they are fertilized by males. The eggs then fall to the bottom or onto vegetation.

conservation status

Not listed by the IUCN.

significance to humans

Common aquarium species.

Splash tetra

Copella arnoldi

family

Lebiasinidae

taxonomy

Copella arnoldi Regan, 1912, Amazon River.

other common names

English: Copeina, jumping characin, splashing tetra, spotted characin, spraying characin; French/Creole: Ti-yaya; German: Spritzsalmler; Finnish: Roiskuttajatetra; Polish: Smuklen pryskacz; Portuguese: Piratanta.

physical characteristics

Small species, reaches a length of only 3 in (8 cm). The slender body is yellowish brown on the back, lighter on the sides, and almost white on the belly. The reddish, long, fanlike fins are particularly pronounced on males. There is a yellow spot at the base of the dorsal fin. Large scales with dark edges cover the body.

distribution

South America in the lower Amazon River basin and coastal portions of the Guyanas.

habitat

Swampy, slow-moving waters that often contain little oxygen.

behavior

Remains near the surface of the water, likely a behavioral adaptation to life in stagnant, low-oxygen waters.

feeding ecology and diet

Feeds on a wide variety of insects and plant matter. Because of its small size and surface-living habits, it is likely preyed on by numerous larger fishes and fish-eating birds.

reproductive biology

Male and female leap out of the water simultaneously and deposit a few eggs in a gelatinous mass on the underside of overhanging vegetation. They repeat this process until 60 or more eggs have been deposited. The male then uses its tail to splash water onto the eggs every 20–30 minutes until they hatch in two to three days. After hatching, the fry fall into the water.

conservation status

Not listed by the IUCN.

significance to humans

Popular as an aquarium fish throughout the world.

Resources

Books

Berra, T. M. Freshwater Fish Distribution. San Diego: Academic Press, 2001.

Gery, J. Characoids of the World. Neptune City, NJ: Tropical Fish Hobbyist Publications, Inc., 1977.

Periodicals

Araujo-Lima, C. A. R. M., and E. C. Oliveira. "Transport of Larval Fish in the Amazon." Journal of Fish Biology 53, Supplement A (1998): 297–306.

Loubens, G. and J. Panfili. "Biologie de Piaractus brachypomus (Teleostei: Serrasalmidae) dans le bassin du Mamoré (Amazonie bolivienne)." Ichthyological Explorations of Freshwaters I 12, no. 1 (2001): 51–64.

Orti, Guillermo, and Axel Meyer. "The Radiation of Characiform Fishes and the Limits of Resolution of Mitochondrial Ribosomal DNA Sequences." Systematic Biology 46, no. 1 (March 1997): 75–100.

Ribeiro, M. C. L. B., and M. Petrere, Jr. "Fisheries Ecology and Management of the Jaraqui (Semaprochilodus taeniurus, S. insignis) in Central Amazonia." Regulated Rivers Research and Management 5, no. 3 (1990): 195–215.

Roberts, T. R. "Osteology and Relationships of the Prochilodontidae, a South American Family of Characoid Fishes." Bulletin of the Museum of Comparative Zoology 145, no. 4 (1973): 213–235.

Ruffino, M. L., and V. J. Isaac. "Life Cycle and Biological Parameters of Several Brazilian Amazon Fish Species." NAGA, The ICLARM Quarterly 18, no. 4 (October 1995): 41–45.

Schrieber, R. "The African Darter Tetra, Nannocharax fasciatus." Tropical Fish Hobbyist 41, no. 4 (1992): 132–135.

Other

FishBase [cited January 22, 2003]. <http://www.fishbase.org/search.cfm>

Ortí, Guillermo, and Richard P. Vari. "Characiformes." [cited January 22, 2003]. <http://www.museum.unl.edu/research/systematics/Orti/>

Katherine E. Mills, MS

Elizabeth Mills, MS