Mirror carp, regionally known as Israeli carp, are a type of domesticated

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 ...

commonly found in

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

but widely introduced or cultivated elsewhere. They are a variety of the

common carp The Eurasian carp or European carp (''Cyprinus carpio''), widely known as the common carp, is a widespread freshwater fish of eutrophic waters in lakes and large rivers in Europe and Asia.Fishbase''Cyprinus carpio'' Linnaeus, 1758/ref>Arkive The ...

(''Cyprinus carpio'') developed through

selective breeding Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant mal ...

. The name "mirror carp" originates from their scales' resemblance to

mirror A mirror or looking glass is an object that Reflection (physics), reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the ...

s. They can grow in excess of – the last few British record fish have all been mirror carp.

Description

Common carp have an even, regular scale pattern, whereas mirrors have irregular, patchy scales that have little to no overlap, making many fish unique and identifiable by sight. As a consequence, most mirror carp in the UK over are nicknamed. Leather carp are another variety of common carp that resemble mirror carp, but are permitted a few scales either along the dorsal line or the wrist of the tail.

Genetics

The most striking difference between mirror and common carp is the presence of large mirror-like scales on the former. The mirror-scale phenotype is caused by a genetic

mutation In biology, a mutation is an alteration in the nucleic acid sequence of the genome of an organism, virus, or extrachromosomal DNA. Viral genomes contain either DNA or RNA. Mutations result from errors during DNA or viral replication, mi ...

present at one of two scale trait loci, denoted by their S and N

allele An allele (, ; ; modern formation from Greek ἄλλος ''állos'', "other") is a variation of the same sequence of nucleotides at the same place on a long DNA molecule, as described in leading textbooks on genetics and evolution. ::"The chro ...

s, respectively. The

genotype The genotype of an organism is its complete set of genetic material. Genotype can also be used to refer to the alleles or variants an individual carries in a particular gene or genetic location. The number of alleles an individual can have in a ...

that produces a mirror scale phenotype is "ssnn" (all recessive), while wild-type carp may have either SSnn or Ssnn genotype. The "S" locus has been identified as containing the gene encoding fibroblast growth factor receptor Fgfr1A1, which was duplicated during the course of carp evolution and consequently does not typically produce lethal phenotypes when only one locus is mutated. The "N" locus has not been identified, but is hypothesized to have bearing on the development of embryonic

mesenchyme Mesenchyme () is a type of loosely organized animal embryonic connective tissue of undifferentiated cells that give rise to most tissues, such as skin, blood or bone. The interactions between mesenchyme and epithelium help to form nearly every o ...

. Contrary to popular belief, a leather carp is not always a mirror carp without scales. Similar to mirror carp, leather, or "nude" carp, are homozygous recessive at the "S" locus, but unlike mirror carp, true leather carp are heterozygous for a dominant mutant allele at the "N" locus (ssNn genotype). Leather carp also have reduced numbers of red blood cells and slower growth rates than scaled carp. Mirror carp from Hungarian and Asian stocks have been observed to have fewer

pharyngeal teeth Pharyngeal teeth are teeth in the pharyngeal arch of the throat of cyprinids, suckers, and a number of other fish species otherwise lacking teeth. A population of mirror carp in

Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...

(there an

invasive species An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species ad ...

) was found to have reverted to full scale cover after being introduced from France in the early twentieth century. The feral Malagasy carp still possessed large scales due to their mirror phenotype, but had increased scale coverage approaching that of wild-type carp. Hubert et al. (2016) found that the recessive allele at the "S" locus was still

fixed Fixed may refer to: * ''Fixed'' (EP), EP by Nine Inch Nails * ''Fixed'', an upcoming 2D adult animated film directed by Genndy Tartakovsky * Fixed (typeface), a collection of monospace bitmap fonts that is distributed with the X Window System * ...

in the population. They believe that the phenotypic reversion was due to compensation by

quantitative trait Complex traits, also known as quantitative traits, are traits that do not behave according to simple Mendelian inheritance laws. More specifically, their inheritance cannot be explained by the genetic segregation of a single gene. Such traits show ...

loci as a result of a selective disadvantage for partial scaling in the wild, perhaps related to an impairment in parasite resistance.

Fishing

A world record mirror carp that weighed was caught in

Hungary Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia a ...

in November 2018. Anglers pursue larger leather carp due to their rarity. The biggest known was

Heather the Leather Heather the Leather (1960 – 1 June 2010) was a 50-year-old scaleless (also known as leather) carp, described as "Britain's most famous fish" before Benson superseded them. Heather was an old and large carp, weighing and despite incorrect all ...

at .

Notes

References

External links