Fishkeeping is a popular hobby, practiced by aquarists, concerned with keeping fish in a home aquarium or garden pond. There is a piscicultural fishkeeping industry, as a branch of agriculture. Fish have been raised as food in ponds for thousands of years. Brightly colored or tame specimens of fish in these pools have sometimes been valued as pets rather than food. Many cultures and modern, have kept fish for both functional and decorative purposes. Ancient Sumerians kept wild-caught fish before preparing them for meals. Depictions of the sacred fish of Oxyrhynchus kept in captivity in rectangular temple pools have been found in ancient Egyptian art. Asia has experienced a long history of stocking rice paddies with freshwater fish suitable for eating, including various types of catfish and cyprinid. Selective breeding of carp into today's popular and domesticated koi and goldfish began over 2,000 years ago in Japan and China, respectively; the Chinese brought goldfish indoors during the Song Dynasty to enjoy them in large ceramic vessels.
In Medieval Europe, carp pools were a standard feature of estates and monasteries, providing an alternative to meat on feast days when meat could not be eaten for religious reasons. Marine fish have been valued for centuries. Wealthy Romans kept other fish in salt water pools. Tertullian reports that Asinius Celer paid 8000 sesterces for a fine mullet. Cicero reports. Rather cynically, he referred to these ancient fishkeepers as the Piscinarii, the "fish-pond owners" or "fish breeders", for example when saying that...the rich did not disguise their jealousy of me. The first person to breed a tropical fish in Europe was Pierre Carbonnier, who founded one of the oldest public aquaria in Paris in 1850, bred the first imported Macropods in 1869, more species. A pioneer of tropical fish breeding, Carbonnier was awarded the Gold Medal of the Imperial French Acclimatization Society in 1875 for research and breeding of exotic freshwater aquarium fish, for his success in introducing exotic fish species to France.
Fishkeepers are known as "aquarists" since many of them are not interested in keeping fish. The hobby can be broadly divided into three specific disciplines, depending on the type of water the fish originate from: freshwater and marine fishkeeping. Freshwater fishkeeping is by far the most popular branch of the hobby, with small pet stores selling a variety of freshwater fish, such as goldfish and angelfish. While most freshwater aquaria are community tanks containing a variety of compatible species, single-species breeding aquaria are popular. Livebearing fish such as mollies and guppies are among those most raised in captivity, but aquarists regularly breed many types of cichlid, characins and killifish. Many fishkeepers create freshwater aquascapes; these aquaria include "Dutch Aquaria" that mass contrasting stem plants, named for European aquarists who first designed them. In recent years, one of the most active advocates of the planted aquarium was the Japanese aquarist Takashi Amano. Garden ponds are in some ways similar to freshwater aquaria, but are much larger and exposed to ambient weather.
In the tropics, tropical fish can be kept in garden ponds. In the temperate zone, species such as goldfish and orfe work better. Marine aquaria have more specific needs and requirements to maintain, the livestock is more expensive; as a result, this branch tends to attract more experienced fishkeepers. Marine aquaria can be exceedingly beautiful, due to the attractive colors and shapes of the corals and the coral reef fish they host. Temperate zone marine fish are not as kept in home aquaria because they do not thrive at room temperature. Coldwater aquaria must provide cooler temperature via a cool room or using a refrigeration device known as a'chiller'. Marine aquarists attempt to recreate a coral reef in their aquaria using large quantities of living rock, porous calcareous rocks encrusted with coralline algae, sponges and other small marine organisms. Larger corals, as well as shrimps, crabs and mollusks are added on, once the aquarium has matured, as well as a variety of small fish; such aquaria are sometimes called reef tanks.
Brackish water aquaria combine elements of the other types, with salinity that must stay between that of freshwater and seawater. Brackish water fish come from habitats with varying salinity, such as mangroves and estuaries, do not thrive if kept permanently in freshwater. Although brackish water aquaria are not familiar to inexperienced aquarists, many species prefer brackish water, including some mollies, many gobies, some pufferfish and scats. Ideal aquarium ecology reproduces. In practice, it is impossible to maintain a perfect balance; as an example, a balanced predator-prey relationship is nearly impossible to maintain in the largest aquaria. An aquarium keeper must maintain balance in the small ecosystems that aquaria provide. Balance is facilitated by larger volumes of water. For example, the death of the only fish in a 10-litre tank causes dramatic changes in the system, while the death of that same fish in a 400-litre tank that holds many fish may create only a minor imbalance. For this reason
Daphnia magna is a small planktonic crustacean that belongs to the subclass Phyllopoda. It inhabits a variety of freshwater environments, ranging from acidic swamps to rivers made of snow runoff, is broadly distributed throughout the Northern Hemisphere and South Africa; the species has been subject of biological research since the 18th century. It is used in ecological and evolutionary studies, in ecotoxicology, it is a popular fish food in aquaria. D. magna is a typical water flea of the genus Daphnia. The females reach up to 5 mm in size, the males about 2 mm, thus they are among the largest species in the genus; the body is protected by a translucent carapace made of a transparent polysaccharide. It has five pairs of thoracic limbs, used to help the filtering process. Spike rows run along the back of the carapace; the intestine has two digestive ceca. The head has a large compound eye. Adult females can be distinguished from those of otherwise similar species such as D. pulex by the absence of a comb on the abdominal claw and the presence of two distinct combs on the abdomen.
The males are smaller than the females and have larger first antennas, a diagnostic feature that distinguishes them from small females. D. magna is a key species in many lentic habitats. It can be found in shallow ponds rich in organic matter sediment. Numerous natural predators can lead to plastic phenotypic responses. In the presence of kairomones, Daphnia spp. develop conspicuous protective structures as an elongated spine and a large body size. It is prey of many planktivorous fishes. Other invertebrate predators are the larvae of the phantom midge Chaoborus and hemipterans and Triops; the large size of the adults protects them from predation from some planktivorous invertebrates. D. magna is widespread in particular in the holarctic. It can be found in fresh and brackish water bodies of different sizes, from lakes to ponds and ephemeral rock pools near the sea. D. magna tolerates higher levels of salinity than most other species of the genus. D. magna is found in the pelagic zone of water bodies, as it feeds on suspended particles in the water column.
Compared to other species of Daphnia, it is more found in association with the substrate where it is able to exploit benthic food sources as periphyton and sediment. The main feeding strategy of D. magna is the filtering of suspended particles. A specialized filtering apparatus, formed by the thoracic appendices, generates a water current within the thoracic opening of the carapace, which permits the collection and the ingestion of unicellular algae and detritus. D. magna can feed on periphyton and detritus, an ability that can offer a competitive advantage to this species over pelagic filter feeders in some environments where suspended food sources might be temporally limited. As most of the other species of the genus Daphnia, D. magna reproduces by cyclical parthenogenesis. This form of reproduction is characterised by the alternating production of asexual offspring and at certain time sexual reproduction through haploid eggs that need to be fertilised; the asexual eggs are diploid and develop into females, or in response to adverse environmental stimuli, into males.
Asexual eggs are released after 3 days. Juveniles go through four to about six moults before becoming mature over a period of 5–10 days. An adult female produces one clutch with up to 100 eggs every 3–4 days until her death, it can live over 3 months in the laboratory at 20 °C. In response to unfavourable environmental conditions, the same female can produce haploid resting eggs, which when fertilised by males, are wrapped within a protective shell called an ephippium; these resting eggs enter a phase of diapause and are able to resist long periods of adverse environmental conditions over a long period of time. Hatching is triggered in response to specific stimuli such as increasing photoperiod and temperatures; the hatchlings from resting eggs develop into females. Some clones of D. magna that do not produce males reproduce by automictic parthenogenesis, in which two haploid cells produced by meiosis fuse to produce a female zygote without fertilisation. This tends to make the resulting daughters homozygous.
The name "water fleas" might come from the typical swimming behavior of Daphnia species, reminiscent of a series of jumps. The movement of the big second antennae generates an upward movement of the whole animal followed by its sinking. Although less common than for other lake dwelling species and horizontal migration patterns of this species have been observed. Diel vertical migration consists in the daily movement of animals from the upper water layers, where they spend the night, to the deep and dark layers, where they spend the day; this behavior reduces exposure of diurnal visual predators by finding refuge in the dark near the bottom and feeding undisturbed during the night in the food-rich upper water layers. The basis of this behaviour is phototactic behavior. In D. magna phototactic behavior has an inducible component. In Diel horizontal migration, D. magna finds ref
Neocaridina davidi is a freshwater shrimp from Taiwan, kept in aquariums. The natural coloration of the shrimp is green-brown. There are a wide range of colors such as red, orange, blue, black, etc. however, the red morph is more sold. The density of coloration on adult shrimp, dependent on breeding, determines their sale price and "quality"; this "quality" is purely aesthetic, as the size and other characteristics of the animal is more or less equal across varieties. Full-grown shrimp reach about 4 centimetres long, they prefer clean water, with a pH of 6.5-8, a temperature of 14–29 °C They are most comfortable at 22 °C. N. davidi shrimp are omnivores that may live 1–2 years. These shrimp have been classified as Neocaridina heteropoda and Neocaridina denticulata sinensis, however are now known as Neocaridina davidi, based on the oldest known published description of the species. N. davidi shrimp are easy to breed well. They will adapt to a wide range of water conditions and will thrive in the same conditions as many common aquarium fish.
Neutral to alkaline pH, with zero ammonia and nitrite as well as low nitrate, gives best results. A cooling system is recommended in warm climates. A few N. davidi shrimp can be kept in a desktop aquarium of 4–8 litres capacity, a setup of 40 l or more will allow for an active colony. A planted tank is most comfortable for the shrimp and the plants provide cover for adults and young. Plants provide surfaces to graze on biofilm; the shrimp spends a great deal of its time sitting on aquatic plants, when available, hiding in them for protection after molting. They eat the film of algae and microorganisms that form on plant leaves without harming the leaves in the process. Java moss and Java fern are both excellent plants for the shrimp tank, as they thrive in the same conditions as the N. davidi shrimp and provide both the physical benefits of the plants to the shrimp and provide a human viewer. Young shrimp spend much of their early life hiding among plants and feeding on microorganisms and tank algae.
Java moss is common and inexpensive in most places, fast-growing, provides excellent cover for the young. N. davidi shrimp respond to the color of their substrate. If they are kept in a tank with light-colored substrate, they will become paler, or transparent. On a darker substrate, they take on their full coloration. Color intensity depends on the types of food available, water pH, temperature. Prepared foods designed for shrimp are available at some suppliers; the N. davidi shrimp is a non-aggressive shrimp. They are active throughout the day, can be seen grazing on biofilm, aquarium décor or the sides of the tank, hunting detritus among the gravel, sometimes mating. Periodically, a shrimp will shed its exoskeleton, leaving an empty white ghost of itself caught in the plants or drifting around the tank; this should be left in the tank, as the shrimp will eat it to recover the valuable minerals it contains. Female pregnant N. davidi shrimp tend to hide in the dark. If they feel endangered by predators, they will abandon their eggs.
They need an environment with wood or plants such as Java moss in which to hide themselves and their babies. When they are carrying the eggs under their bodies, they can be witnessed circulating water over the eggs with their pleopods to ensure good health. N. davidi shrimp are biofilm and algae eaters. They will eat any food intended for aquarium use. Blanched vegetables such as zucchini, baby carrots, cucumber and spinach can be used as a supplemental food but should be fed sparingly. Uneaten vegetables can quickly decompose and create water quality problems. To keep a clean substrate, some shrimp keepers put a glass bowl or glass plate on the bottom as a container for the food. If feeding commercial fish/shrimp food ensure that there is no copper added as this is dangerous for shrimp. Many breeders think. Copper sulfates found in snail killer will kill shrimp; some commercial water conditioners remove or neutralize copper and other metals from tap water in order to make it safe for aquarium life.
The best way to keep a healthy balance in a tank with shrimp is to let them eat all the microorganisms that grow in a tank- including on the glass, on plants, all over driftwood. With a good 8 hours per day of lighting the shrimp will grow to maturity without any problems; the male is less colorful than the female. The male's tail, not being needed to carry eggs, is narrower; the female displays a richer coloration. On the upper section of the female's body, on the "shoulder", the developing eggs on the ovaries may be seen in more transparent individuals; the color of these eggs will depend on the variety of individual shrimp. The shape of the ovaries drapes across both sides of the shrimp, giving rise to the nickname "saddle"; the presence of a "saddle" indicates a female, ready to mate. N. davidi shrimp reach sexual maturity. Breeding only requires a sexed pair of shrimp, stable water parameters, a food source. Eggs may be observed developing in the
Pomacea diffusa, common name the spike-topped apple snail, is a species of freshwater snail, an aquatic gastropod mollusk in the family Ampullariidae, the apple snails. Pomacea diffusa was described as a subspecies of Pomacea bridgesii. Pain argued that Pomacea bridgesii bridgesii was a larger form with a restricted range, with the smaller Pomacea bridgesii diffusa being the common form throughout the Amazon Basin. Cowie and Thiengo suggested that the latter might deserve full species status, the two taxa have been confirmed as distinct species by genetic analyses; the type locality of Pomacea diffusa is in the city of Santa Cruz de la Sierra, although the species is widespread throughout the Amazon Basin. Non-indigenous distribution of Pomacea diffusa include: Thompson recorded this species in Florida in Monroe, Miami-Dade, Palm Beach, Pinellas Counties; the FLMNH electronic database lists samples from Alachua County, but records cited from the FLMNH database for Brevard County are in fact from Broward County.
Rawlings et al. collected this species in Hillsborough and Collier Counties. Pomacea diffusa was first recorded in Florida by William J. Clench; the FLMNH has specimens collected in Palm Beach County in 1967 and Miami-Dade and Broward Counties in the early 1970s. Howells et al. reported its establishment in Mobile, Alabama in 2003. Cuba Pomacea diffusa is known as the spike-topped apple snail, because of its raised spire, it lacks a channeled suture, overlaps in size with the Pomacea paludosa. The egg masses have an irregular honeycombed appearance, like those of Pomacea haustrum, but are smaller and have a tan to salmon color, although the egg masses are white when freshly laid, it is a part of ornamental pet trade for freshwater aquaria. This article incorporates CC-BY-2.0 text from the reference. Applesnails of Florida on the UF / IFAS Featured Creatures Web site
Freshwater snails are gastropod mollusks which live in freshwater. There are many different families, they are found throughout the world in various habitats, ranging from ephemeral pools to the largest lakes, from small seeps and springs to major rivers. The great majority of freshwater gastropods have a shell, with few exceptions; some groups of snails that live in freshwater respire using gills, whereas other groups need to reach the surface to breathe air. In addition, some have both gills and a lung. Most feed on algae. According to a 2008 review of the taxonomy, there are about 4,000 species of freshwater gastropods. At least 33–38 independent lineages of gastropods have colonized freshwater environments, it is not possible to quantify the exact number of these lineages yet, because they have yet to be clarified within the Cerithioidea. From six to eight of these independent lineages occur in North America; the following cladogram is an overview of the main clades of gastropods based on the taxonomy of Bouchet & Rocroi, with families that contain freshwater species marked in boldface: The following cladogram is an overview of the main clades of gastropods based on the taxonomy of Bouchet & Rocroi, modified after Jörger et al. and simplified with families that contain freshwater species marked in boldface: The Neritimorpha are a group of primitive "prosobranch" gilled snails which have a shelly operculum.
Neritiliidae, 5 extant freshwater species Neritidae confined to the tropics the rivers of Europe, family includes the marine "nerites". There are about 110 extant freshwater species; the Caenogastropoda are a large group of gilled operculate snails, which are marine. In freshwater habitats there are ten major families of caenogastropods, as well as several other families of lesser importance: ArchitaenioglossaAmpullariidae, an freshwater family, tropical and includes the large "apple snails" kept in aquaria. 105-170 species. Viviparidae, medium to large snails, live-bearing referred to as "mystery snails". Worldwide except South America, everywhere confined to fresh waters. 125-150 species. SorbeoconchaMelanopsidae, family native to rivers draining to the Mediterranean Middle East, some South Pacific islands. About 25-50 species. Pachychilidae - 165-225 species. Native to South and Central America. Included with the Pleuroceridae by many authors. Paludomidae - about 100 species in south Asia, diverse in African Lakes, Sri Lanka.
Classified with the Pleuroceridae by some authors. Pleuroceridae and diverse in eastern North America high-spired snails of small to large size. About 150 species. Semisulcospiridae, - eastern Asia, Japan the Juga snails of northwestern North America. Included with the Pleuroceridae. About 50 species. Thiaridae, high-spired parthenogenic snails of the tropics, includes those referred to as "trumpet snails" in aquaria. About 110 species. LittorinimorphaLittorinidae - 9 species in the genus Cremnoconchus are freshwater living in streams and waterfalls. Other species are marine. Amnicolidae - about 200 species. Assimineidae - about 20 freshwater species, other are marine Bithyniidae, small snails, native to Eastern Hemisphere. About 130 species. Cochliopidae - 246 species. Helicostoidae, the only species Helicostoa sinensis lives in China. Hydrobiidae, small to small snails found worldwide. About 1250 freshwater species other are marine. Lithoglyphidae - about 100 species. Moitessieriidae - 55 species. Pomatiopsidae, small amphibious snails scattered worldwide, most diverse in eastern and Southeast Asia.
About 170 species. Stenothyridae - about 60 freshwater species, others are marine. NeogastropodaNassariidae - 8-10 freshwater species in the genus Anentome and Clea, native to Southeast Asia. Other Nassariidae are marine. Marginellidae - 2 freshwater species in the genus Rivomarginella, native to Southeast Asia. Other Marginellidae are marine. Lower HeterobranchiaGlacidorbidae - 20 species. Valvatidae, small low-spired snails referred to as "valve snails". 71 species. AcochlidiaceaAcochlidiidae - 5 shell-less species: Acochlidium amboinense, Acochlidium bayerfehlmanni, Acochlidium fijiiensis, Palliohedyle sutteri and Strubellia paradoxa Tantulidae - there is only one species, shell-less Tantulum elegans. Pulmonata, BasommatophoraBasommatophorans are pulmonate or air-breathing aquatic snails, characterized by having their eyes located at the base of their tentacles, rather than at the tips, as in the true land snails Stylommatophora; the majority of basommatophorans have shells that are thin and colorless, all five freshwater basommatophoran families lack an operculum.
Chilinidae, small to medium-sized snails confined to cold South America. About 15 species. Latiidae, small limpet-like snails confined to New Zealand. One or three species. Acroloxidae - about 40 species. Lymnaeidae, found worldwide, but are most numerous in temperate and northern regions; these are the dextral pond snails. About 100 species. Planorbidae, "rams horn" snails, with a worldwide distribution. About 250 species. Physidae, left-handed "pouch snails", native
Invertebrates are animals that neither possess nor develop a vertebral column, derived from the notochord. This includes all animals apart from the subphylum Vertebrata. Familiar examples of invertebrates include arthropods, mollusks and cnidarians; the majority of animal species are invertebrates. Many invertebrate taxa have a greater number and variety of species than the entire subphylum of Vertebrata; some of the so-called invertebrates, such as the Tunicata and Cephalochordata are more related to the vertebrates than to other invertebrates. This makes the invertebrates paraphyletic, so the term has little meaning in taxonomy; the word "invertebrate" comes from the Latin word vertebra, which means a joint in general, sometimes a joint from the spinal column of a vertebrate. The jointed aspect of vertebra is derived from the concept of turning, expressed in the root verto or vorto, to turn; the prefix in- means "not" or "without". The term invertebrates is not always precise among non-biologists since it does not describe a taxon in the same way that Arthropoda, Vertebrata or Manidae do.
Each of these terms describes a valid taxon, subphylum or family. "Invertebrata" is a term of convenience, not a taxon. The Vertebrata as a subphylum comprises such a small proportion of the Metazoa that to speak of the kingdom Animalia in terms of "Vertebrata" and "Invertebrata" has limited practicality. In the more formal taxonomy of Animalia other attributes that logically should precede the presence or absence of the vertebral column in constructing a cladogram, for example, the presence of a notochord; that would at least circumscribe the Chordata. However the notochord would be a less fundamental criterion than aspects of embryological development and symmetry or bauplan. Despite this, the concept of invertebrates as a taxon of animals has persisted for over a century among the laity, within the zoological community and in its literature it remains in use as a term of convenience for animals that are not members of the Vertebrata; the following text reflects earlier scientific understanding of the term and of those animals which have constituted it.
According to this understanding, invertebrates do not possess a skeleton of bone, either internal or external. They include hugely varied body plans. Many have like jellyfish or worms. Others have outer shells like those of insects and crustaceans; the most familiar invertebrates include the Protozoa, Coelenterata, Nematoda, Echinodermata and Arthropoda. Arthropoda include insects and arachnids. By far the largest number of described invertebrate species are insects; the following table lists the number of described extant species for major invertebrate groups as estimated in the IUCN Red List of Threatened Species, 2014.3. The IUCN estimates that 66,178 extant vertebrate species have been described, which means that over 95% of the described animal species in the world are invertebrates; the trait, common to all invertebrates is the absence of a vertebral column: this creates a distinction between invertebrates and vertebrates. The distinction is one of convenience only. Being animals, invertebrates are heterotrophs, require sustenance in the form of the consumption of other organisms.
With a few exceptions, such as the Porifera, invertebrates have bodies composed of differentiated tissues. There is typically a digestive chamber with one or two openings to the exterior; the body plans of most multicellular organisms exhibit some form of symmetry, whether radial, bilateral, or spherical. A minority, exhibit no symmetry. One example of asymmetric invertebrates includes all gastropod species; this is seen in snails and sea snails, which have helical shells. Slugs appear externally symmetrical. Other gastropods develop external asymmetry, such as Glaucus atlanticus that develops asymmetrical cerata as they mature; the origin of gastropod asymmetry is a subject of scientific debate. Other examples of asymmetry are found in hermit crabs, they have one claw much larger than the other. If a male fiddler loses its large claw, it will grow another on the opposite side after moulting. Sessile animals such as sponges are asymmetrical alongside coral colonies. Neurons differ in invertebrates from mammalian cells.
Invertebrates cells fire in response to similar stimuli as mammals, such as tissue trauma, high temperature, or changes in pH. The first invertebrate in which a neuron cell was identified was the medicinal leech, Hirudo medicinalis. Learning and memory using nociceptors in the sea hare, Aplysia has been described. Mollusk neurons are able to detect tissue trauma. Neurons have been identified in a wide range of invertebrate species, including annelids, molluscs and arthropods. One type of invertebrate respi
Procambarus clarkii is a species of cambarid freshwater crayfish, native to northern Mexico, southern and southeastern United States, but introduced elsewhere, where it is an invasive pest. It is known variously as the red swamp crawfish, red swamp crayfish, Louisiana crawfish, Louisiana crayfish or mudbug. P. clarkii is dark red, with long claws and head, small or no spines on the sides of its carapace just below the head, rows of bright red bumps on the front and side of the first leg. The native range of P. clarkii is from northern Mexico and far southeastern New Mexico, through the Gulf States to the Florida Panhandle, as well as north through the Mississippi Basin to southern Illinois and Ohio. It has been introduced, sometimes deliberately, outside its natural range to countries in Asia, Africa and elsewhere in the Americas. In northern Europe, the populations are self maintaining, but not expanding, while in southern Europe, P. clarkii is multiplying and colonising new territory, at the expense of the native crayfish, Astacus astacus and Austropotamobius spp.
Individuals are reported to be able to cross many miles of dry ground in wet seasons, although the aquarium trade and anglers may have hastened the spread in some areas. Attempts have been made to use P. clarkii as a biological control organism, to reduce levels of the snails involved in the lifecycle of schistosomiasis, leading to the dispersal of P. clarkii in, for instance, Kenya. P. clarkii is most found in warm fresh water, such as flowing rivers, reservoirs, irrigation systems and rice paddies. It is considered to be the most ecologically plastic species in the order Decapoda, is able to grow even in only seasonally present water, being able to tolerate dry spells of up to four months. P. clarkii grows and is capable of reaching weights in excess of 50 g, sizes of 5.5–12 cm long. It is able to tolerate saline water, unusual for a crayfish. Additionally, P. clarkii are physiologically capable of tolerating low dissolved oxygen concentrations. The average lifetime of Procambarus clarkii is five years.
Some individuals are known to have reached ages of over six years. The burrowing activities of P. clarkii can lead to damage to water courses and to crops rice, its feeding can disrupt native ecosystems. It may out-compete the native crayfish species, is a vector for the crayfish plague fungus Aphanomyces astaci, for crayfish virus vibriosis, a number of worms parasitic on vertebrates, their burrowing activities may be a threat to civil infrastructure such as storm ponds and levees. Harvests of P. clarkii account for a large majority of the crayfish produced in the United States and elsewhere. Crayfish farming began in Louisiana in the 18th century, taking place in rice fields in a concurrent or alternate culture system; the concurrent culture of rice and crayfish makes good use of land, resources and infrastructure being used for rice production. However, crawfish production has decreased in recent years due to an increase of imports from China, now the world's leading producer of crawfish and is using a rice-based system.
A number of species of crustaceans were introduced to China to create markets for aquaculture and because they are better adapted to growing in a rice field than native fish species. Rice-fish farming originated in China and is once again growing as the yields from Green Revolution practices used to grow rice are no longer increasing, resources such as land and water are becoming more limited. P. Clarkii has been introduced elsewhere for cultivation, such as Spain, where its success is attributable to its ability to colonise disturbed habitats that would be unsuitable for the native crayfish Astacus astacus. P. clarkii is marketed by biological supply companies for teaching and research. P. clarkii exhibits different color morphs, including white and orange and are sold in pet stores. The introduction of P. clarkii has resulted in economic losses in some regions. In the Baixo Mondego region of Portugal, it caused a decrease in 6.3% of profits in rice fields. However, this was on a wet-seeded field.
All negative effects of crawfish can be avoided if adult crawfish are separated from the seed and seedlings. P. clarkii is eaten in the United States, Europe, Africa, Thailand, New Zealand, the Caribbean. About 98% of the crayfish harvested in the United States come from Louisiana, where the standard culinary term is "crawfish". Louisiana in 1990 consumed 70 % locally. Louisiana crawfish are boiled in a large pot with heavy seasoning and other items such as potatoes and corn on the cob. Many differing methods are used to season the dish, there are an equal number of opinions on which one is correct, they are served at a gathering known as a crawfish boil. Procambarus clarkii reproduces sexually, but recent research suggests it may reproduce by parthenogenesis. M. James Norrocky. "Observations on the ecology and growth of the burrowing crayfish Fallicambarus fodiens in North-central Ohio". American Midland Naturalist. 125: 75–86. Doi:10.2307/2426371. JSTOR 2426371. Media related to Procambarus clarkii at Wikimedia Commons Procambarus clarkii at Animal Diversity Web