Tag Archive: freshwater fishes

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii (ray-finned fishes)
Order: Characiformes (Characins)
Family: Characidae (Characins)

Genus/species: Astyanax mexicanus 


GENERAL CHARACTERISTICS: The head is notable for the absence of eyes. Young are born with functioning eyes which become completely enclosed in tissue as fish grows. The lack of sight is compensated by a highly developed lateral line that detects vibrations and changes in the water. The fish is without pigmentation and is plain pink with a silver sheen. They live in schools and grow to about 12 cm or 4.72 inches.


DISTRIBUTION/HABITAT: Texas, New Mexico, and eastern and central Mexico in freshwater pools within dark caves.

DIET IN THE WILD: A keen sense of smell and electrolocation aid in finding food. Blind cave fish are omnivores and feed on animal and plant remains that wash into the caves and on bat droppings from cave ceilings. Much of their time is spent searching for food; they are able to store four times more energy as fat than their surface-dwelling relatives, allowing them to deal with irregular food supplies.


REMARKS: Two forms of A. mexicanus (eyed and eyeless) being members of the same species, are closely related and can interbreed.

The loss of eye tissue in the blind cavefish, which occurs within a few days of their development, happens through epigenetic silencing of eye-related genes, according to a study led by the National Institutes of Health. Epigenetic regulation is a process where genes are turned off or on, typically in a reversible or temporary manner. This mechanism differs from genetic mutations, which are permanent changes in the DNA code. The study appears in Nature Ecology & Evolution.


California Academy of Sciences Steinhart Aquarium Water planet Senses Cluster,  Dr Bart Sheperd

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Read more at: phys.org/news/2018-05-eye-loss-cavefish.html#jCp

NIH phys.org/news/2018-05-eye-loss-cavefish.html

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii (ray-finned fishes)
Order: Lepisosteiformes (Gars) 
Family; Lepisosteidae (Gars)

Genus/species: Atractosteus spatula

GENERAL CHARACTERISTICS: Alligator-like. Large size and broad, short, wide, blunt snout and a heterocercal tail. Color is dark olivaceous brown above and white to yellowish beneath with dark brown blotches on all fins. Body is covered with armor-like ganoid scales consisting of diamond-shaped, interlocking, and extremely hard bony plates covered with layers of dentine and enamel. Head protected by bony plates. Alligator gars have two rows of teeth, a longer one on the palate, and an outer row in the jaw, enabling them to pierce and hold prey. A. spatula is the largest exclusively freshwater fish found in North America.

Alligator gar are the largest gar species. with a length up to than 3 m (9.8 ft), weight to 137 kg (300 pounds).

Alligator Gar 8362889461_f8706ce1f4_b

DISTRIBUTION/HABITAT: Alligator Gar are found in lakes, rivers, and bayous from the Mississippi to the Gulf coast in fresh and brackish water.


DIET IN THE WILD: They are opportunistic carnivores and sit-and-wait predators. They appear to be sluggish, but can ambush prey with short bursts of speed feeding on almost anything, including fish, ducks, turtles, small mammals, and carrion

REPRODUCTION: Females reach sexual maturity at 11 years. Eggs laid on aquatic vegetation, to which they adhere. Young cling to the stems with an adhesive disc on their head until yolk sac is absorbed, and then swim actively. Juveniles feed on plankton, invertebrates, amphibians, and fish before transitioning to fish almost exclusively.
The eggs of alligator gar are bright red and poisonous to humans if ingested.

MORTALITY: Females generally larger and longer lived than males. Some may live to 50 years or more in the wild, 80 years in captivity. The Academies oldest gars are in their 60s.

CONSERVATION STATUS: Not on IUCN Red List. Pollution and degradation of habitat threaten this species.

alligator garIMG_2863


REMARKS: Gars also have a highly vascularized swim bladder directly connected to its throat that enables them to breathe in air, an adaptation to life in water with low oxygen levels. Native Americans used armor-like ganoid scales as arrowheads and jewelry. Early American farmers used the scales on the blades of their plows.

The fossil record traces their existence to the Early Cretaceous over a hundred million years ago.there is no documentation of attacks on man by alligator gars.

There is no documentation of an attack on man by alligator gars.


California Academy of Sciences Steinhart Aquarium Swamp 2018

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fishbase. www.fishbase.se/summary/Atractosteus-spatula.html

ADW. animaldiversity.org/accounts/Atractosteus_spatula/



6-7-13, 1-19-17, 10-9-18

Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii
Order: Siluriformes (Catfish)
Family: Callichthyidae (Callichthyid armored catfishes)

Genus/species: Corydorcas sp.

 Orange Neon Corydoras 3703717946_731674ba1e_b


HABITAT: Fresh water bottom dweller.

DIET IN THE WILD: invertebrates, detritis

REMARKS: All Corys are facultative air breathers, gulping air in oxygen-poor waters absorbing it through its highly vascularized intestine.




California Academy of Sciences, Flooded Rainforest, Cardinal Tetra Exhibit 2018

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Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii (ray-finned fishes)
Order: Cyprinodontiformes (Rivulines, killifishes and live bearers)
Family: Anablepidae (Four-eyed fishes, onesided livebearers)

Genus/species: Anableps sp.   (Anableps, means upward-looking)


GENERAL CHARACTERISTICS: Eyes raised above the top of the head and divided in two different parts, so that they can see below and above the water surface at the same time. Fewer than 80 scales in row above lateral line.

Average length : 14.0 cm (5.5 inches)

DISTRIBUTION/HABITAT: They are found in South America: Trinidad to the Amazon delta in Brazil mainly found in freshwater, sometimes in brackish parts of lagoons and mangrove coastlines


DIET IN THE WILD: Four-eyed Fish spend most of their time at the surface of the water. Their diet mostly consists of terrestrial insects which are readily available at the surface and other invertebrates and diatoms living on the mud, and small fishes.

REMARKS: Anableps sp. can remain on mud bottom exposed to air during low tide.


California Academy of Sciences Steinhart Aquarium Flooded Amazon 2018

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fishbase www.fishbase.org/summary/Anableps-anableps.html

Encyclopedia of life eol.org/pages/26824/overview


Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii (ray-finned fishes)
Order: Characiformes (Characins)
Family: Characidae (Characins)

Genus/species: Paracheirodon axelrodi

GENERAL CHARACTERISTICS: Dark above, Iridescent blue line characteristic of the Paracheirodon species laterally bisecting the fish, with the body below this line being vivid red in color,

Length up to 3 cm (1.1 inch)


DISTRIBUTION/HABITAT: South America: Upper Rio Orinoco and Rio Negro. Found in schools of 12–30 over shoals in the middle water column; non-migratory.

DIET IN THE WILD: Omnivorous, Small crustaceans, worms filamentous algae and fallen fruit.

Cardinal Tetra 10286374786_182498b862_o

MORTALITY and LONGEVITY: The bright, neon, lateral stripe of cardinal tetras makes it difficult for predators to single out and attack an individual. Their schooling behavior also helps to protect individuals from predators.

Adults often perish due to starvation after spring floods when foraging habitats retract during the low water season. They are preyed upon by other fishes including piranha.

Cardinal Tetra live about one year in the wild average 5 years in captivity.

CONSERVATION: IUCN: Not evaluated.


California Academy of Sciences Steinhart Aquarium Flooded Amazon 2018

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Animal diversity web ADW  animaldiversity.org/accounts/Paracheirodon_axelrodi/

fishbase. www.fishbase.org/summary/Paracheirodon-axelrodi.html

Encyclopedia of lifel eol.org/pages/213459/details


Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes (cartilaginous fishes)
Subclass: Elasmobranchii (sharks, rays and skates)
Order: Myliobatiformes
Family: Potamotrygonidae (river stingrays)

Genus/species: Potamotrygon motoro

GENERAL CHARACTERISTICS: Orange-spot Stingrays have an oval disc, with a greyish-brown upper surface patterned with distinct yellow-orange spots, and a white underside. Like most rays, flat teeth are used to grip and crush prey that is sucked into the ventral mouth. Note periscoping eyes which protrude from sand when buried. Olfaction is a major and well-developed means of perception for these stingrays; their olfactory organs are situated in laterally placed cartilaginous capsules on the top of the head. The spine on the tip of the tail is capable of delivering a painful sting.  Rays have an accessory respiratory opening, the Spiracle which is an adapted gill slit which has migrated to the top of the stingray. When the stingray is resting on the bottom the spiracle allows them to breathe.

Length up to 1 m (3 ft.) and weight up to 15 kg (33 lb.)


DISTRIBUTION: South America: Uruguay, Paraná- Paraguay, Orinoco, and Amazon Basins.

HABITAT: P. motoroare found in freshwater calm waters, especially on the sandy margins of lagoons, brooks and streams. They able to tolerate only a narrow range of salinities. Lost ability to retain urea decreasing osmolarity for fresh water unlike salt water relatives.

DIET IN THE WILD: They feed mostly on benthic hard-shelled invertebrates, such as clams, mussels, and crustaceans and also on worms, insect larvae, and small fishes.

REPRODUCTION: Fertilization is internal with the male attaches himself to a female by firmly clamping his jaws onto the posterior margin of her disk, sometimes leaving prominent bite marks. Females produce eggs that hatch inside the female and are then ‘born’ live after a gestation period of no more than three months. The litter size varies, from 3 to 21 young.

LIFESPAN: Maximum of 15 years in captivity.

CONSERVATION: IUCN Red list Data Deficient (DD)

REMARKS: P. motoro is one of the seven species of this genus inhabiting southern South America.

The Operculum pupillare inside the eye which controls the amount of light entering the eye. In dim light it will retract allowing greater light in and better vision at night.

They are not dangerous unless stepped on or threatened.

Fishermen also harpoon these rays during floods when they are found resting over vegetation in shallow water. P.motoro apparently has delicious meat.


California Academy of Sciences Steinhart Aquarium Flooded Forest Floor 2018

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fishbase fishbase.org/summary/Potamotrygon-motoro.html

ARKive  www.arkive.org/ocellate-river-stingray/potamotrygon-motoro/

Encyclopedia of Life eol.org/pages/205366/details

IUCN Red List  www.iucnredlist.org/details/39404/0

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Kingdom: Animalia
Class: Actinopterygii (Ray-finned fishes),
Order: Perciformes (Perch-likes)
Family: Cichlidae (Cichlids).

Genus/species: Heros appendiculatus aka Heros efasciatus

GENERAL CHARACTERISTICS: The compressed body is silvery; five black vertical bars punctuate the lower half of its flanks, a sixth extends to its dorsal fin. (Wild type: wild-type olive-green)

Length up to 14 cm (5.5 inches)

DISTRIBUTION/HABITAT: Native to the Amazon River basin to Upper Orinoco River drainage in Colombia and Venezuela. Green Severum are found in lakes, standing water, or slow-moving water with copious vegetation. Look for young around tree roots.

DIET IN THE WILD: They feed on fruits, seeds, green algae and detritus.

REPRODUCTION: H. appendiculatus are guarders, clutch tenders. Up to 1000 eggs are depoited on flat stones or on roots; both parents participate in caring for eggs and larvae.

Green Severum (juvenile) below




California Academy of Sciences Steinhart Aquarium Amazon Flooded Tunnel 2018

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 fishbase  www.fishbase.org/summary/52199

 Encyclopedia of life  eol.org/pages/203885/details



Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Class: Actinopterygii (ray-finned fishes)
Order: Tetraodontiformes (Puffers and filefishes)
Family: Tetraodontidae (Puffers)

Genus/species: Carinotetraodon travancoricus

GENERAL CHARACTERISTICS: Both sexes are primarily yellow with dark green to black iridescent patches on the flanks and dorsal surface. Males can also have a dark stripe down the center of their pale belly and iridescent “eye wrinkle” patterns that females do not have. Females are more rounded, tend to be a bit larger than males, and may or may not show more smallish spots between their larger dark markings.
Length up to 2.5 cm (one inch)

DISTRIBUTION/HABITAT: C. travancoricus  are found in freshwater rivers of Asia and India. Endemic to the Western Ghats of India

DIET IN THE WILD: The diet of dwarf pufferfish in the wild has not been reported, but other members of the genus feed on zooplankton and various benthic crustaceans and molluscs.


REPRODUCTION: Eggs are deposited and hidden in vegetation.

Results from habitat modifications caused by deforestation and conversion of lands in agricultural areas, increasing urbanization, and over harvesting for the pet trade.


California Academy of Sciences Steinhart Aquarium Water is life feeding

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fishbase www.fishbase.org/summary/Carinotetraodon-travancoricus.html

EOL www.eol.org/pages/222209/details

IUCN  www.iucnredlist.org/details/links/166591/0

Arkive www.arkive.org/malabar-pufferfish/carinotetraodon-travanc…

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Kingdom: Animalia
Phylum: Chordata
Class: Sarcopterygii (lobe-finned fishes)
Order: Ceratodontiformes (Australian lungfishes)
Family: Ceratodontidae (Australian lungfish)

Genus/species: Neoceratodus forsteri

GENERAL CHARACTERISTICS: The brown or olive-brown body is covered with large, bony, overlapping scales. There is some whitish colour on the belly and underside of the head. The dorsal fin originating on the middle of the back is confluent with the caudal and anal fins. The pectoral fins are large and flipper-like just behind the head; the pelvic fins are also flipper-like, situated far back on the body.

3192737183_3ab00093a7_oLength up to nearly 2 m (6 feet)

DISTRIBUTION/HABITAT: Queensland, Australia in rivers with low flow in the austral summer, then restricted to pools that remain. During period of drought, it can tolerate stagnant conditions by breathing air, surfacing 1-2 times per hour; however, it lacks the ability to survive dry spells by aestivation; it is a facultative air-breather that will die if forced to depend on air-breathing.



DIET IN THE WILD: Omnivorous. They use large, crushing teeth on the palate and lower jaw to feed on frogs, tadpoles, fishes, shrimp, earthworms, snails, aquatic plants and native fruits fallen from trees overhanging the creeks. It uses its electroreceptors on its head to pick up hidden mollusks, worms or crustaceans.

REPRODUCTION: First breeds at around 15 years of age in males and 20 years in females. Juveniles are vulnerable to predatory insect larvae, shrimps, fish and wood ducks. Adults have few or no natural predators

MORTALITY/LONGEVITY: Live to more than 65 years in captivity. Some individuals may live to 100 years. It is protected by law.

REMARKS: It is one of six extant representatives of the ancient air-breathing Dipnoi (lungfishes) that flourished during the Devonian period (about 413–365 million years ago) and is the most primitive surviving member of this lineage.

The oldest specimen at the California Academy of Sciences (“Methusela”) arrived from the Melbourne Zoo in 1938. It was half its current size at the time. This species most resembles lungfish fossil forms.

Unlike the African lungfish, this species cannot survive dry spells through estivation. Although the lung supplements the gills during times of oxygen stress, it cannot survive solely by breathing air. The Australian lungfish has only a single lung; the other two lungfish species have paired lungs.


California Academy of Sciences Steinhart Aquarium Water is life

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Fishbase  fishbase.org/summary/4512

ADW animaldiversity.org/accounts/Neoceratodus_forsteri/classi…

EOL eol.org/pages/339109/details

Australian Government  www.environment.gov.au/cgi-bin/sprat/public/publicspecies…

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Kingdom: Animalia
Phylum: Chordata
Class: Actinopterygii (ray-finned fishes)
Order: Cyprinodontiformes (Rivulines, killifishes and live bearers)                                                                                        Family: Poeciliidae

Genus/species: Alafro cultratus

Alafro cultratus16167676782_36fa409f32_k


DISTRIBUTION/HABITAT: Central America: Costa Rica, Panama and Nicaragua. Found in rapidly flowing rainforest streams.

DIET IN THE WILD: Insectivorous, aquatic and terrestrial insects.

REPRODUCTION: Internal live bearers. Gestation lasts for about 24 days. Produces 10 to 30, rarely more, young.



fishbase www.fishbase.gr/summary/46449

Encyclopedia of Life eol.org/pages/1157656/hierarchy_entries/44712641/details

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