Freshwater fish are fish species that spend some or all of their lives in bodies of fresh water such as rivers , lakes and inland wetlands , where the salinity is less than 1.05%. These environments differ from marine habitats in many ways, especially the difference in levels of osmolarity . To survive in fresh water, fish need a range of physiological adaptations .
116-427: The goldfish ( Carassius auratus ) is a freshwater fish in the family Cyprinidae of order Cypriniformes . It is commonly kept as a pet in indoor aquariums , and is one of the most popular aquarium fish . Goldfish released into the wild have become an invasive pest in parts of North America and Australia. Native to China , the goldfish is a relatively small member of the carp family (which also includes
232-475: A synthetic population . In horticulture , the term stable hybrid is used to describe an annual plant that, if grown and bred in a small monoculture free of external pollen (e.g., an air-filtered greenhouse) produces offspring that are "true to type" with respect to phenotype; i.e., a true-breeding organism. Hybridization can occur in the hybrid zones where the geographical ranges of species, subspecies, or distinct genetic lineages overlap. For example,
348-463: A bactrian camel and a dromedary . There are many examples of felid hybrids , including the liger . The oldest-known animal hybrid bred by humans is the kunga equid hybrid produced as a draft animal and status symbol 4,500 years ago in Umm el-Marra , present-day Syria . The first known instance of hybrid speciation in marine mammals was discovered in 2014. The clymene dolphin ( Stenella clymene )
464-438: A generalist species with varied feeding, breeding, and predator avoidance behaviors that contribute to their success. As fish, they can be described as "friendly" towards each other. Very rarely does a goldfish harm another goldfish, nor do the males harm the females during breeding . The only real threat that goldfish present to each other is competing for food. Commons , comets , and other faster varieties can easily eat all
580-633: A hybrid is the offspring resulting from combining the qualities of two organisms of different varieties , subspecies , species or genera through sexual reproduction . Generally, it means that each cell has genetic material from two different organisms, whereas an individual where some cells are derived from a different organism is called a chimera . Hybrids are not always intermediates between their parents such as in blending inheritance (a now discredited theory in modern genetics by particulate inheritance ), but can show hybrid vigor , sometimes growing larger or taller than either parent. The concept of
696-406: A pyruvate decarboxylase – the first known in vertebrates . Although they are a freshwater fish, goldfish have been found in brackish water with a salinity of 17. Goldfish are gregarious, displaying schooling behavior, as well as displaying the same types of feeding behaviors. Goldfish have learned behaviors, both as groups and as individuals, that stem from native carp behavior. They are
812-564: A bear shot by a hunter in the Northwest Territories confirmed the existence of naturally occurring and fertile grizzly–polar bear hybrids . Hybridization between reproductively isolated species often results in hybrid offspring with lower fitness than either parental. However, hybrids are not, as might be expected, always intermediate between their parents (as if there were blending inheritance), but are sometimes stronger or perform better than either parental lineage or variety,
928-515: A considerable seed yield advantage over open pollinated varieties. Hybrid seed dominates the commercial maize seed market in the United States, Canada and many other major maize-producing countries. In a hybrid, any trait that falls outside the range of parental variation (and is thus not simply intermediate between its parents) is considered heterotic. Positive heterosis produces more robust hybrids, they might be stronger or bigger; while
1044-509: A cross between a female horse and a male donkey, and the hinny, a cross between a female donkey and a male horse. Pairs of complementary types like the mule and hinny are called reciprocal hybrids. Polar bears and brown bears are another case of a hybridizing species pairs, and introgression among non-sister species of bears appears to have shaped the Ursidae family tree. Among many other mammal crosses are hybrid camels , crosses between
1160-509: A degree that none of the originally genetically distinct population remains. In agriculture and animal husbandry , the Green Revolution 's use of conventional hybridization increased yields by breeding high-yielding varieties . The replacement of locally indigenous breeds, compounded with unintentional cross-pollination and crossbreeding (genetic mixing), has reduced the gene pools of various wild and indigenous breeds resulting in
1276-602: A donkey as the father. A variety of mechanisms limit the success of hybridization, including the large genetic difference between most species. Barriers include morphological differences, differing times of fertility, mating behaviors and cues, and physiological rejection of sperm cells or the developing embryo. Some act before fertilization; others after it. In plants, some barriers to hybridization include blooming period differences, different pollinator vectors, inhibition of pollen tube growth, somatoplastic sterility, cytoplasmic-genic male sterility and structural differences of
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#17327724366861392-574: A few bigger goldfish that people don't think of as record holders, perhaps in ornamental lakes". In July 2010, a goldfish measuring 16 inches (41 cm) and 5 pounds (2.3 kg) was caught in a pond in Poole , England, thought to have been abandoned there after outgrowing a tank. On November 16, 2020, a 15-inch (38 cm) goldfish weighing 9 pounds (4.1 kg) was found in a 16 acres (6.5 ha) lake in Greenville, South Carolina , while conducting
1508-562: A goldfish is determined by their diet, water quality, and exposure to light, along with age and health. Because goldfish eat live plants, their presence in a planted aquarium can be problematic. Only a few aquarium plant species, such as Cryptocoryne and Anubias , can survive around goldfish, but they require special attention so that they are not uprooted. Goldfish are popular pond fish, since they are small, inexpensive, colorful, and very hardy. In an outdoor pond or water garden , they may even survive for brief periods if ice forms on
1624-548: A group of about 50 natural hybrids between Australian blacktip shark and the larger common blacktip shark was found by Australia's eastern coast in 2012. Russian sturgeon and American paddlefish were hybridized in captivity when sperm from the paddlefish and eggs from the sturgeon were combined, unexpectedly resulting in viable offspring. This hybrid is called a sturddlefish . The two genera Asymmetron and Branchiostoma are able to produce viable hybrid offspring, even if none have lived into adulthood so far, despite
1740-500: A hybrid is interpreted differently in animal and plant breeding, where there is interest in the individual parentage. In genetics , attention is focused on the numbers of chromosomes . In taxonomy, a key question is how closely related the parent species are. Species are reproductively isolated by strong barriers to hybridization, which include genetic and morphological differences, differing times of fertility, mating behaviors and cues, and physiological rejection of sperm cells or
1856-555: A large amount of waste both in their feces and through their gills , releasing harmful chemicals into the water. Buildup of this waste to toxic levels can occur in a relatively short period of time, and can easily cause a goldfish's death. For common and comet varieties, each goldfish should have about 20 US gallons (76 L; 17 imp gal) of water. Smaller fantail goldfish should have about 10 US gallons (38 L; 8.3 imp gal) per goldfish. The water surface area determines how much oxygen diffuses and dissolves into
1972-439: A long time, both intentionally for purposes such as biological control , and unintentionally, as with accidental escapes of individuals. Introductions can drastically affect populations, including through hybridization. There is a kind of continuum with three semi-distinct categories dealing with anthropogenic hybridization: hybridization without introgression, hybridization with widespread introgression (backcrossing with one of
2088-498: A mate among the species that raised it, instead of the species of its biological parents. Cagebird breeders sometimes breed bird hybrids known as mules between species of finch , such as goldfinch × canary . Among amphibians, Japanese giant salamanders and Chinese giant salamanders have created hybrids that threaten the survival of Japanese giant salamanders because of competition for similar resources in Japan. Among fish,
2204-758: A more pointed snout, while the snout of C. carassius is well rounded. C. gibelio often has a grayish/greenish color, while crucian carp are always golden bronze. Juvenile crucian carp have a black spot on the base of the tail, which disappears with age. In C. auratus , this tail spot is never present. C. auratus have fewer than 31 scales along the lateral line, while crucian carp have 33 scales or more. Goldfish can hybridize with some other Carassius species of carp. Koi and common carp may also interbreed with goldfish to produce sterile hybrids. Wild goldfish typically grow to between 4.7 inches (12 cm) and 8.7 inches (22 cm) but can reach 16 inches (41 cm). The size of pet goldfish depends upon its breed. As of April 2008,
2320-531: A pan-North American study, the main cause being human pollution. The number of fish species and subspecies to become endangered has risen from 40 to 61, since 1989. For example, the Bigmouth Buffalo is now the oldest age-validated freshwater fish in the world, and its status urgently needs reevaluation in parts of its endemic range. About 2 ⁄ 3 of the total freshwater fisheries in China are in
2436-432: A phenomenon called heterosis, hybrid vigour, or heterozygote advantage . This is most common with plant hybrids. A transgressive phenotype is a phenotype that displays more extreme characteristics than either of the parent lines. Plant breeders use several techniques to produce hybrids, including line breeding and the formation of complex hybrids. An economically important example is hybrid maize (corn), which provides
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#17327724366862552-430: A population survey of Oak Grove Lake. As a domestic fish, thus an easily accessible model organism , goldfish have one of the most studied senses of vision in fishes . Goldfish have four kinds of cone cells , which are respectively sensitive to different colors: red, green, blue and ultraviolet . The ability to distinguish between four different primary colors classifies them as tetrachromats . Goldfish have one of
2668-412: A significant temperature change, often in spring. Males chase gravid female goldfish (females carrying eggs), and prompt them to release their eggs by bumping and nudging them. Goldfish, like all cyprinids , are egg-layers. Their eggs are adhesive and attach to aquatic vegetation, typically dense plants such as Cabomba or Elodea or a spawning mop. The eggs hatch within 48 to 72 hours. Within
2784-405: A species, such as between different breeds . Single cross hybrids result from the cross between two true-breeding organisms which produces an F1 hybrid (first filial generation). The cross between two different homozygous lines produces an F1 hybrid that is heterozygous ; having two alleles , one contributed by each parent and typically one is dominant and the other recessive . Typically,
2900-515: A tank for several weeks, sometimes months, it becomes possible to feed a goldfish by hand without it shying away. Goldfish have a memory-span of at least three months and can distinguish between different shapes, colors, and sounds. By using positive reinforcement , goldfish can be trained to recognize and to react to light signals of different colors or to perform tricks. Fish respond to certain colors most evidently in relation to feeding. Fish learn to anticipate feedings provided they occur at around
3016-586: A tendency to produce red, orange , or yellow color mutations ; this was first recorded in Imperial China , during the Jin dynasty (266–420) . During the Tang dynasty (AD 618–907), it was popular to raise carp in ornamental ponds and water gardens . A natural genetic mutation produced gold (actually yellowish orange) rather than silver coloration. People began to selectively breed the gold variety instead of
3132-448: A traditional game called goldfish scooping is played, in which a player scoops goldfish from a basin with a special scooper. Sometimes bouncy balls are substituted for goldfish. Although edible and closely related to some fairly widely eaten species, goldfish are rarely eaten. A fad among American college students for many years was swallowing goldfish as a stunt and as a fraternity initiation process. The first recorded instance
3248-562: A week or so, the fry begins to assume its final shape, although a year may pass before they develop a mature goldfish color; until then they are a metallic brown like their wild ancestors. In their first weeks of life, the fry grow quickly—an adaptation born of the high risk of getting devoured by the adult goldfish (or other fish and insects) in their environment. Some highly selectively bred goldfish can no longer breed naturally due to their altered shape. The artificial breeding method called "hand stripping" can assist in breeding, but can harm
3364-410: A wide range of conditions, preferring a water temperature around 80 °F (27 °C). Warmwater fish can survive cold winter temperatures in northern climates, but thrive in warmer water. Common warmwater fish include catfish , largemouth bass , bluegill , crappies , and many other species from the family Centrarchidae . In 2021, a group of conservation organizations estimated that one-third of
3480-577: Is a hybrid of two Atlantic species, the spinner and striped dolphins . In 2019, scientists confirmed that a skull found 30 years earlier was a hybrid between the beluga whale and narwhal , dubbed the narluga . Hybridization between species is common in birds. Hybrid birds are purposefully bred by humans, but hybridization is also common in the wild. Waterfowl have a particularly high incidence of hybridization, with at least 60% of species known to produce hybrids with another species. Among ducks , mallards widely hybridize with many other species, and
3596-407: Is a hybridization test widely used in genetics to determine whether two separately isolated mutants that have the same (or similar) phenotype are defective in the same gene or in different genes (see Complementation (genetics) article). If a hybrid organism containing the genomes of two different mutant parental organisms displays a wild type phenotype, it is ordinarily considered that
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3712-571: Is a particularly common mechanism for speciation in plants, and is now known to be fundamental to the evolutionary history of plants. Plants frequently form polyploids , individuals with more than two copies of each chromosome. Whole genome doubling has occurred repeatedly in plant evolution. When two plant species hybridize, the hybrid may double its chromosome count by incorporating the entire nuclear genome of both parents, resulting in offspring that are reproductively incompatible with either parent because of different chromosome counts. Human impact on
3828-566: Is a vital part of aquatic ecosystem stability, so changes to stream and river water temperature can have large impacts on biotic communities. Many aquatic larvae use thermal cues to regulate their life cycles, mostly notably here, insects. Insects are a large part of most fish diets, so this can pose a great dietary problem. Temperature can cause changes in fish behavior and distribution habits as well by increasing their metabolic rates and thus their drive to spawn and feed. Linear systems are more easily fragmented and connectivity in aquatic ecosystems
3944-659: Is also more occasionally done in the livestock and pet trades; some well-known wild × domestic hybrids are beefalo and wolfdogs . Human selective breeding of domesticated animals and plants has also resulted in the development of distinct breeds (usually called cultivars in reference to plants); crossbreeds between them (without any wild stock ) are sometimes also imprecisely referred to as "hybrids". Hybrid humans existed in prehistory. For example, Neanderthals and anatomically modern humans are thought to have interbred as recently as 40,000 years ago. Mythological hybrids appear in human culture in forms as diverse as
4060-451: Is always sterile worker ants (and because ants are haplodiploid , unfertilized eggs become males). Without mating with males of the other species, the queens are unable to produce workers, and will fail to establish a colony of their own. Plant species hybridize more readily than animal species, and the resulting hybrids are fertile more often. Many plant species are the result of hybridization, combined with polyploidy , which duplicates
4176-575: Is defined as a species that does not naturally occur in a certain area or ecosystem. This includes eggs and other biological material associated with the species. Non-native species are considered invasive if they cause ecological or economic injury. The introduction of exotic fish species into ecosystems is a threat to many endemic populations. The native species struggle to survive alongside exotic species which decimate prey populations or outcompete indigenous fishes. High densities of exotic fish are negatively correlated with native species richness. Because
4292-552: Is derived from Latin hybrida , used for crosses such as of a tame sow and a wild boar. The term came into popular use in English in the 19th century, though examples of its use have been found from the early 17th century. Conspicuous hybrids are popularly named with portmanteau words , starting in the 1920s with the breeding of tiger–lion hybrids ( liger and tigon ). From the point of view of animal and plant breeders, there are several kinds of hybrid formed from crosses within
4408-597: Is invasive worldwide, and there are multiple efforts to remove them from their non-native ecosystems. Both species are among the " 100 of the World’s Worst Invasive Alien Species ," as determined by the IUCN Invasive Species Specialist Group based on their effect on anthropogenic activities, environmental biodiversity and their ability to act as a case study for important ecological issues. Hybridization involves
4524-424: Is often due to poor care. The lifespan of goldfish in captivity can extend beyond 10 years. If left in the dark for a period of time, goldfish gradually change color until they are almost gray. Goldfish produce pigment in response to light, similarly to how human skin becomes tanned in the sun. Fish have cells called chromatophores that produce pigments that reflect light and give the fish coloration. The color of
4640-427: Is that hybrid individuals can form a "bridge" transmitting potentially helpful genes from one species to another when the hybrid backcrosses with one of its parent species, a process called introgression . Hybrids can also cause speciation , either because the hybrids are genetically incompatible with their parents and not each other, or because the hybrids occupy a different niche than either parent. Hybridization
4756-515: Is the proper time to give up on a population that is becoming a hybrid swarm, or to try and save the still existing pure individuals. Once a population becomes a complete mixture, the goal becomes to conserve those hybrids to avoid their loss. Conservationists treat each case on its merits, depending on detecting hybrids within the population. It is nearly impossible to formulate a uniform hybridization policy, because hybridization can occur beneficially when it occurs "naturally", and when hybrid swarms are
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4872-484: Is turned off at night, can kill them, especially if the tank is small. Care must also be taken when adding water, as the new water may be of a different temperature. Temperatures under about 10 °C (50 °F) are dangerous to fancy varieties, though commons and comets can survive slightly lower temperatures. Extremely high temperatures (over 30 °C (86 °F)) can also harm goldfish. However, higher temperatures may help fight protozoan infestations by accelerating
4988-442: Is vital. Freshwater fishes are particularly vulnerable to habitat destruction because they reside in small bodies of water which are often very close to human activity and thus easily polluted by trash, chemicals, waste, and other agents which are harmful to freshwater habitats. Land use changes cause major shifts in aquatic ecosystems. Deforestation can change the structure and sedimentary composition of streams, which impacts
5104-653: The Minotaur , blends of animals, humans and mythical beasts such as centaurs and sphinxes , and the Nephilim of the Biblical apocrypha described as the wicked sons of fallen angels and attractive women. Hybridization between species plays an important role in evolution, though there is much debate about its significance. Roughly 25% of plants and 10% of animals are known to form hybrids with at least one other species. One example of an adaptive benefit to hybridization
5220-654: The Prussian carp and the crucian carp ). It was first selectively bred for color in imperial China more than 1,000 years ago, where several distinct breeds were developed. Goldfish breeds vary greatly in size, body shape, fin configuration, and coloration (various combinations of white, yellow, orange, red, brown, and black are known). Various species of carp (collectively known as Asian carp ) have been bred and reared as food fish for thousands of years in East Asia . Some of these normally gray or silver species have
5336-587: The United States . There has been considerable debate about the taxonomy of the goldfish. Previously, the goldfish was believed to be either a subspecies of the crucian carp ( Carassius carassius ), or of the Prussian carp ( Carassius gibelio ). However, modern genetic sequencing has suggested otherwise, and that modern goldfish are domesticated varieties of C. auratus that are native to Southern China. C. auratus are differentiated from other Carassius species by several characteristics. C. auratus have
5452-509: The guppy and mosquitofish , goldfish (and other carp) are frequently added to stagnant bodies of water in an attempt to reduce mosquito populations, which spread the vectors of diseases such as West Nile virus , malaria , and dengue . However, introducing goldfish has often had negative consequences for local ecosystems , and their efficacy as pest control has never been compared to those of native fishes. The market for live goldfish and other crucian carp usually imported from China
5568-593: The parasite 's life cycle—thus eliminating it more quickly. The optimum temperature for goldfish is between 20 and 22 °C (68 and 72 °F). Like all fish, goldfish do not like to be petted. In fact, touching a goldfish can endanger its health, because it can cause the protective slime coat to be damaged or removed, exposing the fish's skin to infection from bacteria or water-borne parasites. However, goldfish respond to people by surfacing at feeding time, and can be trained or acclimated to taking pellets or flakes from human fingers. The reputation of goldfish dying quickly
5684-472: The sea urchin Strongylocentrotus purpuratus (female) and the sand dollar Dendraster excentricus (male). When two distinct types of organisms breed with each other, the resulting hybrids typically have intermediate traits (e.g., one plant parent has red flowers, the other has white, and the hybrid, pink flowers). Commonly, hybrids also combine traits seen only separately in one parent or
5800-514: The southern United States at high elevation . Common coldwater fish include brook trout , rainbow trout , and brown trout . Coolwater fish species prefer water temperature between the coldwater and the long warmwater species, around 60 to 80 °F (16–27 °C). They are found throughout North America except for the southern portions of the United States. Common coolwater species include muskellunge , northern pike , walleye , and yellow perch . Warmwater fish species can survive in
5916-438: The "suture region". It is at these regions that the subspecies were formed. Other hybrid zones have formed between described species of plants and animals. From the point of view of genetics, several different kinds of hybrid can be distinguished. A genetic hybrid carries two different alleles of the same gene , where for instance one allele may code for a lighter coat colour than the other. A structural hybrid results from
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#17327724366866032-522: The "wild" original. However, some variations are hardier, such as the Shubunkin. Currently, there are about 300 breeds recognized in China. The vast majority of goldfish breeds today originated from China. Some of the main varieties are: Chinese tradition classifies goldfish into four main types. These classifications are not commonly used in the West. Like most species in the carp family, goldfish produce
6148-451: The 1620s, goldfish were highly regarded in southern Europe because of their metallic scales, and symbolized good luck and fortune. It became a tradition for married men to give their wives a goldfish on their first anniversary, as a symbol for the prosperous years to come. This tradition quickly died, as goldfish became more available, losing their status. Goldfish were first introduced to North America around 1850 and quickly became popular in
6264-506: The F1 generation is also phenotypically homogeneous, producing offspring that are all similar to each other. Double cross hybrids result from the cross between two different F1 hybrids (i.e., there are four unrelated grandparents). Three-way cross hybrids result from the cross between an F1 hybrid and an inbred line. Triple cross hybrids result from the crossing of two different three-way cross hybrids. Top cross (or "topcross") hybrids result from
6380-494: The Nile perch into Lake Victoria, possibly to improve sport fishing and boost the fishery. In the 1980s, the Nile perch population saw a large increase which coincided with a great increase in the value of the fishery. This surge in Nile perch numbers restructured the lake's ecology. The endemic cichlid population, known to have around 500 species, was cut almost in half. By the 1990s, only three species of sport fish were left to support
6496-788: The Yangtze Basin. Many Yangtze fish species have declined drastically and 65 were recognized as threatened in the 2009 Chinese red list . The Chinese paddlefish , once common to the Yangtze River, is one of a number of extinctions to have taken place due to the degradation of the Yangtze, alongside that of the wild Yangtze sturgeon . Intentional anthropogenic reconstruction and rerouting of waterways impacts stream flow, water temperature, and more, impacting normal habitat functionality. Dams not only interrupt linear water flow and cause major geological channel shifts, but also limit
6612-551: The amount of water available to fishes in lakes, streams and rivers and have the potential to change the trophic structure because of these alterations of the habitat and the limitations to movement and connectivity. Unnatural water flow below dams causes immense habitat degradation, reducing viable options for aquatic organisms. Upstream migration is hindered by the dam structure and can cause population declines as fishes don't have access to normal feeding and/or spawning grounds. Dams tend to affect upstream species richness, that is,
6728-405: The bodily salt concentration on a level lower than the surroundings, and vice versa. Many species solve this problem by associating different habitats with different stages of life. Both eels, anadromous salmoniform fish and the sea lamprey have different tolerances in salinity in different stages of their lives. Among fishers in the United States, freshwater fish species are usually classified by
6844-524: The butterfly Limenitis arthemis has two major subspecies in North America, L. a. arthemis (the white admiral) and L. a. astyanax (the red-spotted purple). The white admiral has a bright, white band on its wings, while the red-spotted purple has cooler blue-green shades. Hybridization occurs between a narrow area across New England, southern Ontario, and the Great Lakes,
6960-426: The chromosomes. A few animal species are the result of hybridization. The Lonicera fly is a natural hybrid. The American red wolf appears to be a hybrid of the gray wolf and the coyote , although its taxonomic status has been a subject of controversy. The European edible frog is a semi-permanent hybrid between pool frogs and marsh frogs ; its population requires the continued presence of at least one of
7076-547: The chromosomes. Chromosome duplication allows orderly meiosis and so viable seed can be produced. Plant hybrids are generally given names that include an "×" (not in italics), such as Platanus × hispanica for the London plane, a natural hybrid of P. orientalis (oriental plane) and P. occidentalis (American sycamore). The parent's names may be kept in their entirety, as seen in Prunus persica × Prunus americana , with
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#17327724366867192-481: The common pheasant and hen golden pheasant ( Chrysolophus pictus ). Spurs are absent in hybrids of the former type, although present in both parents. Hybridization is greatly influenced by human impact on the environment, through effects such as habitat fragmentation and species introductions. Such impacts make it difficult to conserve the genetics of populations undergoing introgressive hybridization . Humans have introduced species worldwide to environments for
7308-400: The crossing of a top quality or pure-bred male and a lower quality female, intended to improve the quality of the offspring, on average. Population hybrids result from the crossing of plants or animals in one population with those of another population. These include interspecific hybrids or crosses between different breeds. In biology, the result of crossing of two populations is called
7424-431: The depth should be at least 80 centimeters (31 in) to preclude freezing. During winter, goldfish become sluggish, stop eating and often stay on the bottom of the pond. This is normal; they become active again in the spring. Unless the pond is large enough to maintain its own ecosystem without interference from humans, a filter is important to clear waste and keep the pond clean. Plants are essential as they act as part of
7540-444: The developing embryo . Some act before fertilization and others after it. Similar barriers exist in plants, with differences in flowering times, pollen vectors, inhibition of pollen tube growth, somatoplastic sterility, cytoplasmic-genic male sterility and the structure of the chromosomes. A few animal species and many plant species, however, are the result of hybrid speciation , including important crop plants such as wheat , where
7656-551: The diet of goldfish consists of crustaceans , insects , and various plant matter. Like most fish, they are opportunistic feeders and do not stop eating on their own accord. Overfeeding can be deleterious to their health, typically by blocking the intestines . This happens most often with selectively bred goldfish, which have a convoluted intestinal tract. When excess food is available, they produce more waste and feces , partly due to incomplete protein digestion. Overfeeding can sometimes be diagnosed by observing feces trailing from
7772-407: The diverse Heliconius butterflies , but that is disputed. The two closely related harvester ant species Pogonomyrmex barbatus and Pogonomyrmex rugosus have evolved to depend on hybridization. When a queen fertilizes her eggs with sperm from males of her own species, the offspring is always new queens. And when she fertilizes the eggs with sperm from males of the other species, the offspring
7888-413: The doubling of chromosome sets, causing immediate genetic isolation. Hybridization may be important in speciation in some plant groups. However, homoploid hybrid speciation (not increasing the number of sets of chromosomes) may be rare: by 1997, only eight natural examples had been fully described. Experimental studies suggest that hybridization offers a rapid route to speciation, a prediction confirmed by
8004-611: The environment has resulted in an increase in the interbreeding between regional species, and the proliferation of introduced species worldwide has also resulted in an increase in hybridization. This has been referred to as genetic pollution out of concern that it may threaten many species with extinction. Similarly, genetic erosion from monoculture in crop plants may be damaging the gene pools of many species for future breeding. The conservation impacts of hybridization between species are highly debated. While hybridization could potentially threaten rare species or lineages by "swamping"
8120-580: The exotic species is suddenly introduced to a community, it does not have any established predators or prey. The exotic species then have a survival advantage over endemic organisms. One such example is the destruction of the endemic cichlid population in Lake Victoria via the introduction of the predatory Nile perch ( Lates niloticus ). Although the exact time is unknown, in the 1950s the Ugandan Game and Fisheries Department covertly introduced
8236-499: The extinction of the yellowfin cutthroat trout ( Oncorhynchus clarkii macdonaldi ) found only in the Twin Lakes of Colorado, USA. The yellowfin cutthroat trout was discovered in 1889 and was recognized as a subspecies of the cutthroat trout ( Oncorhynchus clarkii ). The rainbow trout was introduced to Colorado in the 1880s. By 1903, the yellowfin cutthroat trout stopped being reported. It is now presumed extinct. The rainbow trout
8352-429: The fact that early generation hybrids and ancient hybrid species have matching genomes, meaning that once hybridization has occurred, the new hybrid genome can remain stable. Many hybrid zones are known where the ranges of two species meet, and hybrids are continually produced in great numbers. These hybrid zones are useful as biological model systems for studying the mechanisms of speciation. Recently DNA analysis of
8468-405: The filtration system, as well as a food source for the fish. Plants are further beneficial since they raise oxygen levels in the water. Like their wild ancestors, common and comet goldfish as well as shubunkin can survive, and even thrive, in any climate that can support a pond. In general, when released into the wild, goldfish quickly take over the waterways as an invasive species . In the wild,
8584-456: The fish if not done correctly. In captivity, adults may also eat young that they encounter. Goldfish are able to survive short periods of entirely anoxic conditions . Survival is shorter under higher temperatures, suggesting that this is a cold weather adaptation . Researchers speculate that this is specifically an adaptation to survival in frozen water bodies over winter. Energy is obtained from liver glycogen . This process depends upon
8700-429: The fish's cloaca . Goldfish-specific food has less protein and more carbohydrate than conventional fish food. Enthusiasts may supplement this diet with shelled peas (with outer skins removed), blanched green leafy vegetables , and bloodworms . Young goldfish benefit from the addition of brine shrimp to their diet. As with all animals, goldfish preferences vary. Like some other well-known aquarium fish, such as
8816-555: The food during a feeding before varieties can reach it. This can lead to stunted growth or possible starvation of fancier varieties when they are kept in a pond with their single-tailed brethren. As a result, care should be taken to combine only breeds with similar body type and swim characteristics. Goldfish have strong associative learning abilities, as well as social learning skills. In addition, their visual acuity allows them to distinguish between individual humans . Owners may notice that fish react favorably to them (swimming to
8932-410: The front of the glass, swimming rapidly around the tank, and going to the surface mouthing for food) while hiding when other people approach the tank. Over time, goldfish learn to associate their owners and other humans with food, often "begging" for food whenever their owners approach. Goldfish that have constant visual contact with humans also stop considering them to be a threat . After being kept in
9048-565: The fusion of gametes that have differing structure in at least one chromosome, as a result of structural abnormalities . A numerical hybrid results from the fusion of gametes having different haploid numbers of chromosomes . A permanent hybrid results when only the heterozygous genotype occurs, as in Oenothera lamarckiana , because all homozygous combinations are lethal. In the early history of genetics, Hugo de Vries supposed these were caused by mutation . Genetic complementation
9164-507: The genetic relationships between ducks are further complicated by the widespread gene flow between wild and domestic mallards. One of the most common interspecific hybrids in geese occurs between Greylag and Canada geese ( Anser anser x Branta canadensis ). One potential mechanism for the occurrence of hybrids in these geese is interspecific nest parasitism , where an egg is laid in the nest of another species to be raised by non-biological parents. The chick imprints upon and eventually seeks
9280-630: The genetically "pure" individuals with hybrids, hybridization could also save a rare lineage from extinction by introducing genetic diversity. It has been proposed that hybridization could be a useful tool to conserve biodiversity by allowing organisms to adapt, and that efforts to preserve the separateness of a "pure" lineage could harm conservation by lowering the organisms' genetic diversity and adaptive potential, particularly in species with low populations. While endangered species are often protected by law, hybrids are often excluded from protection, resulting in challenges to conservation. The term hybrid
9396-460: The habitat functionality for many fish species and can reduce species richness, evenness, and diversity. Agriculture, mining, and basic infrastructural building can degrade freshwater habitats. Fertilizer runoffs can create excess nitrogen and phosphorus which feed massive algae blooms that block sunlight, limit water oxygenation, and make the habitat functionally unsustainable for aquatic species. Chemicals from mining and factories make their way into
9512-401: The hybrids are more fit and have breeding advantages over the indigenous ecotype or species. These hybridization events can result from the introduction of non-native genotypes by humans or through habitat modification, bringing previously isolated species into contact. Genetic mixing can be especially detrimental for rare species in isolated habitats, ultimately affecting the population to such
9628-605: The imperial family were forbidden to keep goldfish of the gold (yellow) variety, yellow being the imperial color . During the Ming dynasty (1368–1644), goldfish also began to be raised indoors, which permitted selection for mutations that would not be able to survive in ponds. The first occurrence of -tailed goldfish was recorded in the Ming dynasty. In 1603, goldfish were introduced to Japan . In 1611, goldfish were introduced to Portugal and from there to other parts of Europe . During
9744-404: The international Iranian diaspora , goldfish is a traditional part of Nowruz celebrations. Goldfish are usually placed on Haft-sin tables as a symbol of progress. Freshwater fish 41.24% of all known species of fish are found in fresh water. This is primarily due to the rapid speciation that the scattered habitats make possible. When dealing with ponds and lakes, one might use
9860-764: The largest goldfish in the world was believed by the BBC to measure 19 inches (48 cm), in the Netherlands . At the time, a goldfish named "Goldie", kept as a pet in a tank in Folkestone , England, was measured as 15 inches (38 cm) and over 2 pounds (0.91 kg), and named as the second largest in the world behind the Netherlands fish. The secretary of the Federation of British Aquatic Societies (FBAS) stated of Goldie's size, "I would think there are probably
9976-410: The last require specialized care. Ramshorn snails are helpful by eating any algae that grows in the pond. Without some form of animal population control , goldfish ponds can easily become overstocked. Fish such as orfe consume goldfish eggs. Ponds small and large are fine in warmer areas, though goldfish can "overheat" in small volumes of water in the summer in tropical climates. In frosty climes,
10092-400: The loss of genetic diversity . Since the indigenous breeds are often well-adapted to local extremes in climate and have immunity to local pathogens, this can be a significant genetic erosion of the gene pool for future breeding. Therefore, commercial plant geneticists strive to breed "widely adapted" cultivars to counteract this tendency. Familiar examples of equid hybrids are the mule,
10208-682: The low oxygen and very high ammonia / nitrite levels inherent in such an environment. In comparison to other common aquarium fish, goldfish have high oxygen needs and produce a large amount of waste due to the fact they lack a stomach; therefore they require a substantial volume of well-filtered water to thrive. In addition, all goldfish varieties have the potential to reach 5 inches (130 mm) in total length, with single-tailed breeds often exceeding 1 foot (0.30 m). Single-tailed varieties include common and comet goldfish. In many countries, carnival and fair operators commonly give goldfish away in plastic bags as prizes . In late 2005 Rome banned
10324-460: The mating of two genetically different species ( interspecific hybridization ). It is dangerous for native species to hybridize because hybrid phenotypes may have better fitness and outcompete the two parent species and/or other fishes in the ecosystem. This could irreversibly compromise the genetic identity of one or both of the parent species and even drive them to extinction if their range is limited. The rainbow trout discussed above hybridized with
10440-428: The most studied senses of hearing in fish . They have two otoliths , permitting the detection of sound particle motion, and Weberian ossicles connecting the swim bladder to the otoliths, facilitating the detection of sound pressure . Goldfish can only grow to sexual maturity with enough water and the right nutrition. Most goldfish breed in captivity , particularly in pond settings. Breeding usually happens after
10556-583: The native greenback cutthroat trout ( Oncorhynchus clarkii stomias ), causing their local extinction in the Twin Lakes area of Colorado as their hybrid " cutbows " became more prevalent. The rainbow trout has been reported to hybridize with at least two other salmonid species. Additionally, the cichlids in Lake Victoria evolved over 700 unique species in only 150,000 years and are theorized to have done so via ancient hybridization events which led to speciation. Hybrid (biology) In biology ,
10672-452: The number of chromosomes has been doubled. A form of often intentional human-mediated hybridization is the crossing of wild and domesticated species. This is common in both traditional horticulture and modern agriculture ; many commercially useful fruits, flowers, garden herbs, and trees have been produced by hybridization. One such flower, Oenothera lamarckiana , was central to early genetics research into mutationism and polyploidy. It
10788-498: The number of fish species in the ecological community. Additionally, dams can cause the isolation of fish populations, and the lack of connectivity creates possible problems for inbreeding and low genetic diversity. The loss of connectivity impacts the structure of community assemblies and increases the fragmentation of habitats, which can compound existing problems for vulnerable species. Temperature alterations are another unintended consequence of dam and land use projects. Temperature
10904-422: The once multispecies fishery, two of which were invasive. More recent research has suggested that remaining cichlids are recovering due to the recent surge in Nile perch commercial fishing, and the cichlids that are left have the greatest phenotypic plasticity and are able to react to environmental changes quickly. The introduction of the rainbow trout ( Oncorhynchus mykiss ) in the late 19th century resulted in
11020-420: The only remaining evidence of prior species, they need to be conserved as well. Regionally developed ecotypes can be threatened with extinction when new alleles or genes are introduced that alter that ecotype. This is sometimes called genetic mixing. Hybridization and introgression, which can happen in natural and hybrid populations, of new genetic material can lead to the replacement of local genotypes if
11136-438: The other (e.g., a bird hybrid might combine the yellow head of one parent with the orange belly of the other). Interspecific hybrids are bred by mating individuals from two species, normally from within the same genus. The offspring display traits and characteristics of both parents, but are often sterile , preventing gene flow between the species. Sterility is often attributed to the different number of chromosomes between
11252-573: The parent species), and hybrid swarms (highly variable populations with much interbreeding as well as backcrossing with the parent species). Depending on where a population falls along this continuum, the management plans for that population will change. Hybridization is currently an area of great discussion within wildlife management and habitat management. Global climate change is creating other changes such as difference in population distributions which are indirect causes for an increase in anthropogenic hybridization. Conservationists disagree on when
11368-537: The parent species. Cave paintings indicate that the European bison is a natural hybrid of the aurochs and the steppe bison . Plant hybridization is more commonplace compared to animal hybridization. Many crop species are hybrids, including notably the polyploid wheats : some have four sets of chromosomes (tetraploid) or six (hexaploid), while other wheat species have (like most eukaryotic organisms) two sets ( diploid ), so hybridization events likely involved
11484-506: The parents' common ancestor living tens of millions of years ago. Among insects, so-called killer bees were accidentally created during an attempt to breed a strain of bees that would both produce more honey and be better adapted to tropical conditions. It was done by crossing a European honey bee and an African bee . The Colias eurytheme and C. philodice butterflies have retained enough genetic compatibility to produce viable hybrid offspring. Hybrid speciation may have produced
11600-637: The point of view of taxonomy , hybrids differ according to their parentage. Hybrids between different subspecies (such as between the dog and Eurasian wolf ) are called intra-specific hybrids. Interspecific hybrids are the offspring from interspecies mating ; these sometimes result in hybrid speciation. Intergeneric hybrids result from matings between different genera, such as between sheep and goats . Interfamilial hybrids, such as between chickens and guineafowl or pheasants , are reliably described but extremely rare. Interordinal hybrids (between different orders) are few, but have been engineered between
11716-580: The same basic models of speciation as when studying island biogeography . Freshwater fish differ physiologically from saltwater fish in several respects. Their gills must be able to diffuse dissolved gases while keeping the electrolytes in the body fluids inside. Their scales reduce water diffusion through the skin : freshwater fish that have suffered too much scale loss will die. They also have well developed kidneys to reclaim salts from body fluids before excretion . Many species of fish do reproduce in freshwater, but spend most of their adult lives in
11832-414: The same time every day. As with many other examples of animal , selective breeding of goldfish over centuries has produced several color variations, some of them far removed from the " golden " color of the original fish. There are also different body shapes, and fin and eye configurations. Some extreme versions of the goldfish live only in aquariums —they are much less hardy than varieties closer to
11948-461: The sea. These are known as anadromous fish, and include, for instance, salmon , trout , sea lamprey and three-spined stickleback . Some other kinds of fish are, on the contrary, born in salt water, but live most of or parts of their adult lives in fresh water; for instance the eels . These are known as catadromous fish . Species migrating between marine and fresh waters need adaptations for both environments; when in salt water they need to keep
12064-532: The silver variety, keeping them in ponds or other bodies of water. On special occasions at which guests were expected, they would be moved to a much smaller container for display. By the Song dynasty (AD 960–1279), the selective domestic breeding of goldfish was firmly established. In 1162, the empress of the Song dynasty ordered the construction of a pond to collect the red and gold variety. By this time, people outside
12180-653: The soil and go into streams via runoff. More runoff makes its way into streams since paved roads, cement, and other basic infrastructure do not absorb materials, and all the harmful pollutants go directly into rivers and streams. Fish are very sensitive to changes in water pH, salinity, hardness, and temperature which can all be affected by runoff pollutants and indirect changes from land use. Freshwater fish face extinction due to habitat loss, overfishing, and " forever chemicals ." Conservation efforts, sustainable practices, and awareness are crucial in maintaining fish populations and species diversity. An exotic (or non-native) species
12296-488: The surface, as long as there is enough oxygen remaining in the water and the pond does not freeze solid. Common, London and Bristol shubunkins, jikin, wakin, comet and some hardier fantail goldfish can be kept in a pond year-round in temperate and subtropical climates. Moor, veiltail, oranda and lionhead can be kept safely in outdoor ponds year-round only in more tropical climates and elsewhere only in summer months. Compatible fish include rudd , tench , orfe and koi , but
12412-470: The term negative heterosis refers to weaker or smaller hybrids. Heterosis is common in both animal and plant hybrids. For example, hybrids between a lion and a tigress (" ligers ") are much larger than either of the two progenitors, while " tigons " (lioness × tiger) are smaller. Similarly, the hybrids between the common pheasant ( Phasianus colchicus ) and domestic fowl ( Gallus gallus ) are larger than either of their parents, as are those produced between
12528-400: The two parental mutant organisms are defective in different genes. If the hybrid organism displays a distinctly mutant phenotype, the two mutant parental organisms are considered to be defective in the same gene. However, in some cases the hybrid organism may display a phenotype that is only weakly (or partially) wild-type, and this may reflect intragenic (interallelic) complementation. From
12644-462: The two species. For example, donkeys have 62 chromosomes , horses have 64 chromosomes, and mules or hinnies have 63 chromosomes. Mules, hinnies, and other normally sterile interspecific hybrids cannot produce viable gametes, because differences in chromosome structure prevent appropriate pairing and segregation during meiosis , meiosis is disrupted, and viable sperm and eggs are not formed. However, fertility in female mules has been reported with
12760-523: The use of goldfish and other animals as carnival prizes. Rome has also banned the use of "goldfish bowls", on animal cruelty grounds, as well as Monza , Italy, in 2004. In the United Kingdom , the government proposed banning this practice as part of its Animal Welfare Bill, though this has since been amended to only prevent goldfish being given as prizes to unaccompanied minors. In Japan , during summer festivals and religious holidays ( ennichi ),
12876-441: The water temperature in which they survive. The water temperature affects the amount of oxygen available as cold water contains more oxygen than warm water. Coldwater fish species survive in the coldest temperatures, preferring a water temperature of 50 to 60 °F (10–16 °C). In North America, air temperatures that result in sufficiently cold water temperatures are found in the northern United States, Canada, and in
12992-405: The water. A general rule is have 1 square foot (0.093 m). Active aeration by way of a water pump , filter or fountain effectively increases the surface area agitation. The goldfish is classified as a coldwater fish , and can live in unheated aquaria at a temperature comfortable for humans. However, rapid changes in temperature, for example in an office building in winter when the heat
13108-437: The world's freshwater fish species were at risk of extinction. A global assessment of freshwater fishes estimates an average decline of 83% in populations between 1970 and 2014. The protection of 30% of Earth's surfaces by 2030 may encompass freshwater habitat and help protect these threatened species. There is an increasing trend in freshwater fish for local taxonomic, functional, and phylogenetic richness in more than half of
13224-490: The world's rivers. This increase in local diversity is primarily explained by anthropogenic species introductions that compensate for or even exceed extinctions in most rivers. A study and an interactive map by EWG using its results show freshwater fish in the U.S. ubiquitously contain high levels of harmful PFAS , with a single serving typically significantly increasing the blood PFOS level. About four in ten North American freshwater fish are endangered, according to
13340-587: Was $ 1.2 million in 2018. Some high quality varieties cost between $ 125 and $ 300. Fishbowls are detrimental to the health of goldfish and are prohibited by animal welfare legislation in several municipalities. The practice of using bowls as permanent fish housing originated from a misunderstanding of Chinese "display" vessels: goldfish which were normally housed in ponds were, on occasion, temporarily displayed in smaller containers to be better admired by guests. Goldfish kept in bowls or "mini-aquariums" suffer from death, disease, and stunting , due primarily to
13456-444: Was in 1939 at Harvard University . The practice gradually fell out of popularity over the course of several decades and is rarely practiced today. Some animal advocates have called for boycotts of goldfish purchases, citing industrial farming and low survival rates of the fish. In Chinese history, goldfish was seen "as a symbol of luck and fortune". Moreover, only members of the Song dynasty could own goldfish. In Iran and among
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