The European bitterling (''Rhodeus amarus'') is a

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. The term excludes seawater and brackish water, but it does include non-salty mi ...

ray-finned fish Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of sk ...

belonging to the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Acheilognathidae The bitterling-like cyprinids form the cyprinoid family Acheilognathidae. This subfamily contains seven genera, although the Khanka spiny bitterling is often placed in ''Acheilognathus'', and at least 75 described species to date. Over half of t ...

, the bitterlings. It originates in Europe, ranging from the Rhone River basin in

France France, officially the French Republic, is a country located primarily in Western Europe. Overseas France, Its overseas regions and territories include French Guiana in South America, Saint Pierre and Miquelon in the Atlantic Ocean#North Atlan ...

to the

Neva River The Neva ( , ; , ) is a river in northwestern Russia flowing from Lake Ladoga through the western part of Leningrad Oblast (historical region of Ingria) to the Neva Bay of the Gulf of Finland. Despite its modest length of , it is the fourth-l ...

Russia Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...

. It was originally described as ''Cyprinus amarus'' by

Marcus Elieser Bloch Marcus Elieser Bloch (1723–1799) was a German physician and naturalist who is best known for his contribution to ichthyology through his multi-volume catalog of plates illustrating the fishes of the world. Brought up in a Hebrew-speaking Jewish ...

in 1782, and has been referred to in scientific literature as ''Rhodeus sericeus amarus''. It is known simply as "the bitterling" in its native

range Range may refer to: Geography * Range (geographic), a chain of hills or mountains; a somewhat linear, complex mountainous or hilly area (cordillera, sierra) ** Mountain range, a group of mountains bordered by lowlands * Range, a term used to i ...

, where it is the only

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

of its

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Rhodeus ''Rhodeus'' is a genus of freshwater ray-finned fishes belonging to the family Acheilognathidae, the bitterlings. The scientific name is derived from the Greek word ', meaning "rose". Most species in the genus are restricted to Asia, but two sp ...

'', and sometimes in the scientific literature, also, but this is technically wrong, being a leftover from the times when the European bitterling was united with its

Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...

n relative, the

Amur bitterling The Amur bitterling (''Rhodeus sericeus'') is a small fish of the carp family. It is sometimes just called "bitterling", which dates back to the time when the European bitterling ('' Rhodeus amarus'') was still considered conspecific with ''R. ...

, in ''R. sericeus''. Properly, "bitterling" can refer to any species of ''

Acheilognathus ''Acheilognathus'' iis a genus of freshwater ray-finned fishes belonging to the family Acheilognathidae, the bitterlings. The fishes in this genus are found in Asia. The name is derived from the Greek ''a'', meaning "without", the Greek ''chei ...

'' or ''Rhodeus''. The fish reaches a size of up to . It is found among plants over

sand Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural ...

y and muddy bottoms in shallow waters. It feeds mainly on plants, and to a lesser extent, upon worms,

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

s, and

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

larvae. This species of fish was once used for human pregnancy tests. Female specimens were injected with the

urine Urine is a liquid by-product of metabolism in humans and many other animals. In placental mammals, urine flows from the Kidney (vertebrates), kidneys through the ureters to the urinary bladder and exits the urethra through the penile meatus (mal ...

of the woman to be tested. If the woman was

pregnant Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

, the hormones in the urine would cause the fish's

ovipositor The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typica ...

s to protrude. The fish spawns in clear, slow-running or still water, often with a muddy bottom. The female deposits her eggs inside freshwater

mussel Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and Freshwater bivalve, freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other ...

s. The male sheds his

sperm Sperm (: sperm or sperms) is the male reproductive Cell (biology), 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 ...

into the inhalent current of the respiring mussel and thereby fertilizes the eggs. The young hatch and remain protected within the mussel for about a month, eventually leaving the mussel as actively swimming larvae. Both sexes reach sexual maturity in 1 year, at a length of . LayingtubeBitterling

References

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European bitterling The European bitterling (''Rhodeus amarus'') is a temperate freshwater ray-finned fish belonging to the family Acheilognathidae, the bitterlings. It originates in Europe, ranging from the Rhone River basin in France to the Neva River in Russia. ...

Freshwater fish of Europe

Habitats Directive species