The bronze corydoras (''Corydoras aeneus''), green corydoras, bronze catfish, lightspot corydoras or wavy catfish is a

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...

fish in the "armored catfish" family,

Callichthyidae Callichthyidae is a family of catfishes ( order Siluriformes), called armored catfishes due to the two rows of bony plates (or scutes) along the lengths of their bodies. It contains some of the most popular freshwater aquarium fish, such as many ...

, often kept in captivity by fish keepers. It is widely distributed in

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on the eastern side of the

Andes The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...

, from

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and

Trinidad Trinidad is the larger and more populous of the two major islands of Trinidad and Tobago. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is often referred to as the southernmos ...

to the

Río de la Plata The Río de la Plata (, "river of silver"), also called the River Plate or La Plata River in English, is the estuary formed by the confluence of the Uruguay River and the Paraná River at Punta Gorda. It empties into the Atlantic Ocean and fo ...

basin. It was originally described as ''Hoplosoma aeneum'' by

Theodore Gill Theodore Nicholas Gill (March 21, 1837 – September 25, 1914) was an American ichthyologist, mammalogist, malacologist and librarian. Career Born and educated in New York City under private tutors, Gill early showed interest in natural histor ...

in 1858 and has also been referred to as ''Callichthys aeneus''.

Appearance and anatomy

The adult size is 6½ cm for males and a slightly larger 7 cm for females (2½ to 2¾ inches). Females have a slightly higher body frame than males in accordance with their larger abdominal region. Their average life span is 10 years. It has a yellow or pink body, white belly, and is blue-grey over its head and back. Its fins are yellow or pink and immaculate. In common with most Corydoras the dorsal, pectoral and adipose fins have an additional sharp barb and have a mild poison which causes fish which try to attack them to get stung. A brownish-orange patch is usually present on the head, just before the dorsal fin, and is its most distinctive feature when viewed from above in the stream. Their upper sides are often a greenish color, which is the reason another common name for this fish is the green corydoras. Like many other catfishes, females are larger than males in this species.

Ecology

They are found in quiet, shallow waters with soft bottoms that can sometimes be heavily polluted by clouds of disturbed mud from the bottom, but it also inhabits running waters. In its native habitat, it inhabits waters with a temperature range of 25 °C to 28 °C (77 °F to 82 °F), pH 6.0–8.0, and

hardness In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...

5 to 19 DGH. Like most members of the genus ''Corydoras'', these

catfish Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...

have a unique method of coping with the low

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as wel ...

content that prevails in such environments. In addition to utilizing their

gills A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are ...

like any other

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 li ...

, they rapidly come to the surface of the water and draw air in through their mouth. This air is then absorbed through the wall of the intestine and any surplus air is expelled through the

vent Vent or vents may refer to: Science and technology Biology *Vent, the cloaca region of an animal *Vent DNA polymerase, a thermostable DNA polymerase Geology *Hydrothermal vent, a fissure in a planet's surface from which geothermally heated water ...

. It typically stays in

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of 20 to 30 individuals. It feeds on

worm Worms are many different distantly related bilateral animals that typically have a long cylindrical tube-like body, no limbs, and no eyes (though not always). Worms vary in size from microscopic to over in length for marine polychaete wor ...

benthic The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from ancient Greek, βένθος (bénthos), meaning "t ...

crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...

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 pairs ...

s, and plant matter.

Reproduction

Reproduction occurs with the onset of the rainy season, which changes the water chemistry. Females spawn 10–20 egg-clutches with multiple males at a time, but an entire egg clutch is inseminated by the sperm of a single male. In laboratory observations, it was found that bronze corydoras have a unique method of insemination. When these fish reproduce, the male will present his abdomen to the female. The female will attach her mouth to the male's genital opening, creating the well-known "T-position" many ''Corydoras'' exhibit during courtship. The female will then drink the

sperm Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, whi ...

. The sperm rapidly moves through her intestines and is discharged together with her eggs into a pouch formed by her pelvic fins. The female can then swim away and deposit the pouch somewhere else alone. Because the T-position is exhibited in other species than just ''C. aeneus'', it is likely that they also exhibit this behavior. In the wild, eggs are laid on waterweeds. Males do not form territories or compete over females; interference between males might only happen when two males present their abdomens simultaneously. On the other hand, females do not choose between males. Mating is more or less random; therefore, male reproductive success is directly related to courtship frequency. The eggs of ''C. aeneus'' exhibit a unique surface pattern with small villi-like protuberances which resemble attaching-filaments of teleost eggs. These structures allow the eggs to be adhesive and stick to a specific place or to each other. The presence of these structures may be related to the turbid habitat in which this species lives.

In the aquarium

Bronze corydoras are probably the most popular ''Corydoras'' species. It is annually bred and shipped in large quantities all over the world It is easily bred and is produced in commercial quantities in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

, Europe, and

Singapore Singapore (), officially the Republic of Singapore, is a sovereign island country and city-state in maritime Southeast Asia. It lies about one degree of latitude () north of the equator, off the southern tip of the Malay Peninsula, borde ...

. Most of the available fish are therefore domestic strains. Wild imports are reported to be less easy to breed. They are a hardy and useful aquarium fish despite having a coloration that is by no means striking or unusual. Many

aquarist An aquarist is a person who manages aquariums, either professionally or as a hobby. They typically care for aquatic animals, including fish and marine invertebrates. Some may care for aquatic mammals. Aquarists often work at public aquariums. They ...

s are fascinated by the habits of these fish. They ceaselessly comb the bottom of the aquarium for food and therefore disturb it slightly, sending up

detritus In biology, detritus () is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts commun ...

and waste material that has settled loosely on the bottom. They prefer being kept in

groups A group is a number of persons or things that are located, gathered, or classed together. Groups of people * Cultural group, a group whose members share the same cultural identity * Ethnic group, a group whose members share the same ethnic iden ...

of 5 or more, being sociable fish and are ideal fish for a

community tank Community aquaria are tanks that are designed to contain more than one species of fish. Most commonly they include a variety of species that do not normally occur together in nature, for example angelfish from Brazil, swordtails from Mexico, and ...

. Other ''

Corydoras ''Corydoras'' is a genus of freshwater catfish in the family Callichthyidae and subfamily Corydoradinae. The species usually have more restricted areas of endemism than other callichthyids, but the area of distribution of the entire genus almost ...

'' species can be placed in the same aquarium, and despite the strong resemblance many species bear to one another, the species will tend to separate out and only move about among their own kind. ''Corydoras aeneus'' is not particular about the composition of the water. Adequate conditions are a temperature range of 20 to 28 °C (68 to 82 °F), pH of 6.0–8.0, and hardness of 2–30 DGH. The water should have no salt added to it. A fairly dense growth of plants with a number of possible hiding places is greatly appreciated. Corys are easy to feed, they are

omnivore An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutr ...

s eating all flake and pelleted food and also live and frozen foods. When it comes to sperm, then the female glues the

eggs Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...

, only a few in number, to the chosen substrate and then (sometimes) quickly touches them with her mouth. After several acts of spawning, which span a total of two to three hours, one female will have produced up to 200 eggs. Frequently, two males are used for each female, as one male has difficulty fertilizing all the eggs. The eggs gradually grow darker in color, and just prior to hatching (ranging from three days at 28 °C to a week at 20 °C) they turn dark brown. The fry keep to the bottom of the tank, feeding on detritus and any fine foods available. The parents may spawn again within two to three weeks. Corydoras Albino

Albino corydoras

The albino corydoras is an

albino Albinism is the congenital absence of melanin in an animal or plant resulting in white hair, feathers, scales and skin and pink or blue eyes. Individuals with the condition are referred to as albino. Varied use and interpretation of the term ...

variety of the bronze corydoras that has been developed for the aquarium trade, with a pale pink or orange body and red eyes. It is physically similar to normally-colored individuals, although some breeders report that the fry are a little slower to develop. Others say that the albinos are practically blind and that the males are somewhat sterile, although this may be due to extensive inbreeding. Albino bronze corydoras are frequently injected with bright dye (via a needle) and sold in aquariums. This controversial practice is known as "

painting Painting is the practice of applying paint, pigment, color or other medium to a solid surface (called the "matrix" or "support"). The medium is commonly applied to the base with a brush, but other implements, such as knives, sponges, and ...

" or "juicing" fish.

References

External links

Corydoras from egg to larva
(German) {{Taxonbar, from=Q741269 Corydoras Taxa named by Theodore Gill Fish described in 1858