Ceratothoa oestroides | |
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Class: | Malacostraca |
Order: | Isopoda |
Family: | Cymothoidae |
Genus: | Ceratothoa |
Species: | C. oestroides |
Binomial name | |
Ceratothoa oestroides (Risso, 1826) | |
Synonyms [1] | |
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Ceratothoa oestroides is a crustacean isopod, [1] obligate ectoparasite of marine fish that dwells in the buccal cavity. It is the causative agent of various pathologies including tissue damage at the parasitisation site (tongue), growth defects, decrease in mean host weight and size and increases mortalities in farmed and wild fish populations. [2] It has been recorded in six different fish families: Sparidae ( Boops boops , Diplodus annularis , Pagelus erythrinus , Spicara smaris, Sparus aurata ), Carangidae ( Trachurus mediterraneus ), Clupeidae ( Sardina pilchardus ), Maenidae, Scorpenidae ( Scorpaena notata, Scorpaena porcus ), and Mugilidae ( Liza aurata ). [3] [4]
Adult male and female mate in the host buccal cavity (Fig. 1). Embryos develop in the female marsupium, where offspring pass through different pullus stages until they are released from the marsupium as free swimming manca, ready for infecting fish hosts. C. oestroides is one of the most devastating ectoparasites in Mediterranean aquaculture, with an unequal distribution along different geographical areas [5] [6] [7] [8]
The life cycle of Cymothoidae, which are protandric hermaphrodites, [9] encompasses mating of adult male and female in the host buccal cavity, development of embryos in the female marsupium followed by moulting through pullus stages (I–IV stages). The first pullus (I stage) can be found only in the marsupium where it moults into second pullus (II stage). Although most Cymothoidae have pullus stages I–IV, only pullus stages I and II seem to exist in Ceratothoa oestroides (Fig. 2).[ citation needed ]
Sexual differentiation occurs only after young leave the brood pouch. [10] As free swimming manca (infective stage), the parasite will seek and attach to an appropriate host, and will then moult, losing the swimming setae and becoming immotile. The parasite attaches on the host body (flanks, fins), and then crawls towards the operculum, where it enters the buccal cavity and settles on the base of the tongue. After permanent attachment is completed, another moult follows. A seventh segment and pair of pereopods appears, typical for the isopod pre-adult form. An isopod in this pre-adult form will function as male until conditions require it to transform in to female. Sexual transformation is a complex process and depends on many factors. After transformation into female (Figs. 3 and 4), the isopod is known as an adult. [11] Alternatively, individuals that are first to reach the buccal cavity may undergo sexual differentiation (male puberty, mature male, transitory male stage, female puberty, mature female). Females block sexual differentiation of a second individual parasite within a host. This second individual remains in the mature male stage as long as the female is alive. All the life stages of C. oestroides are found on the fish host, if we also include the pulli that are situated in the female pouch.[ citation needed ]
This parasite causes various pathologies, including tissue damage of the tongue, growth defects, anaemia, decrease in mean host weight and size and increased mortalities in farmed and wild fish populations. [2] It has not been observed to impair feed intake in pre- and harvest-sized fish. Instead, the decrease in fingerlings’ weight is likely attributed to the suspected hematophagous nature of the parasite. Athanassopoulou et al. (1999) [12] noticed that Ceratothoa-infected fish are also infected with Rickettsia-like organisms (RLO), and related the latter pathogen to transmission by the isopod. Apparently, infection of RLO is higher in Ceratothoa -highly infected farms [7] (Vagianou et al. 2006). Vagianou et al. (2006) [7] observed that larval stages of C. oestroides (pulli II) that attack small fish induce the most damage, causing severe ulcers and extensive granulomatous lesions in the eyes that lead to blindness or the total loss of the eyeball. However, this was not reported in other geographic area where the isopod has been found in reared fish. Fish infected with adult parasites did not show serious pathology. Lesions were localized at the upper and lower jaws and the tongue.
Growth of farmed fish can be depressed and fish can suffer from post-haemorrhagic anaemia. [13] Growth of market size caged fish infected with the parasite can be reduced by up to 20% compared to market size, uninfected caged fish. [14] For example, parasitised sea bass ( Dicentrarchus labrax ) in the age group of 291–293 days had reduced growth by 20.1% (14 g) and reduced length of 7.1% (12.63 mm) compared to non-parasitised fish. [5]
C. oestroides infection is easily diagnosed by examining the buccal cavity and determining the presence of the parasite.[ citation needed ]
Treatment of isopod infestations on young fish has been attempted with success by means of hourly formalin baths and manual removing from the buccal cavity during the vaccination for other diseases.[ citation needed ]
Within a fish farm, it is common practice to decrease the number of wild fish population by fish net, as well as periodically clean the floating cages nets, depending on the season. Horton and Okamura (2001) suggest grading of smaller and larger fish and their separation, mooring the cages in deeper sites with sufficient currents to disperse the juvenile parasites in a direction away from the cages. [5] Often, in cases of heavy parasitism and mortality, reducing the fish density is enough to remedy the situation.
Cymothoa exigua, or the tongue-eating louse, is a parasitic isopod of the family Cymothoidae. It enters fish through the gills. The female attaches to the tongue, while the male attaches to the gill arches beneath and behind the female. Females are 8–29 mm (0.3–1.1 in) long and 4–14 mm (0.16–0.55 in) wide. Males are about 7.5–15 mm (0.3–0.6 in) long and 3–7 mm (0.12–0.28 in) wide. The parasite severs the blood vessels in the fish's tongue, causing the tongue to fall off. It then attaches itself to the remaining stub of tongue and the parasite itself effectively serves as the fish's new "tongue".
Sea lice are copepods of the family Caligidae within the order Siphonostomatoida. They are marine ectoparasites that feed on the mucus, epidermal tissue, and blood of host fish. The roughly 559 species in 37 genera include around 162 Lepeophtheirus and 268 Caligus species.
The European seabass, also known as the Branzino, European bass, sea bass, common bass, white bass, capemouth, white salmon, sea perch, white mullet, sea dace or Loup de Mer, is a primarily ocean-going fish native to the waters off Europe's western and southern and Africa's northern coasts, though it can also be found in shallow coastal waters and river mouths during the summer months and late autumn. It is one of only six species in its family, Moronidae, collectively called the temperate basses.
Enteric redmouth disease, or simply redmouth disease is a bacterial infection of freshwater and marine fish caused by the pathogen Yersinia ruckeri. It is primarily found in rainbow trout and other cultured salmonids. The disease is characterized by subcutaneous hemorrhaging of the mouth, fins, and eyes. It is most commonly seen in fish farms with poor water quality. Redmouth disease was first discovered in Idaho rainbow trout in the 1950s. The disease does not infect humans.
The gilt-head bream, also known as the gilthead, gilt-head seabream or silver seabream, is a species of marine ray-finned fish belonging to the family Sparidae, the seabreams or porgies. This fish is found in the Eastern Atlantic and the Mediterranean. It is a highly esteemed food fish and an important species in aquaculture.
The Cymothoidae are a family of isopods in the suborder Cymothoida found in both marine and freshwater environments. Cymoithoids are ectoparasites, usually of fish, and they include the bizarre "tongue-biter", which attaches to a fish's tongue, causing it to atrophy, and replaces the tongue with its own body. Ceratothoa oestroides is one of the most devastating ectoparasites in Mediterranean aquaculture. Around 40 genera and more than 380 species of cymothoid are recognised. Species of the Cymothoidae are generally found in warmer waters and rarely in the cool and cold climates.
Paramoeba is a genus of common parasites, including species that can cause infection in fish, crabs, sea urchins and others.
Gnathia pilosus is the eighth gnathiid species to be described from South Africa. It occurs on the warmer east coast compared to the other seven gnathiids found on the colder west and south coasts of South Africa. Gnathiids have a polymorphic and biphasic life cycle. There are three larval stages with each stage having two forms, namely praniza and zuphea. The praniza is usually a replete, haematophagous phase while the zuphea is an unfed benthic dweller phase. Adults can be found in groups with a single male and up to 43 females and immature specimens. The free-living adults do not feed and are usually hidden in a cavity or sponge where reproduction will occur. The larvae of gnathiid isopods are known to parasitise a large variety of intertidal fish worldwide. The taxonomic classification of gnathiids is usually based on the morphological characteristics of the adult male. The detailed descriptions of the female and larva, however, are also important for identifying these life stages to species level when collected in the absence of males.
Lernaeocera branchialis, sometimes called cod worm, is a parasite of marine fish, found mainly in the North Atlantic. It is a marine copepod which starts life as a small pelagic crustacean larva. It is among the largest of copepods, ranging in size from 2 to 3 millimetres when it matures as a copepodid larva to more than 40 mm as a sessile adult.
The spotted seabass is a species of ray-finned fish belonging to the family Moronidae, the temperate basses. This species is found in the marine and brackish waters of the coastal eastern Atlantic Ocean from the English Channel to the Canary Islands and Senegal, as well as through the Mediterranean Sea.
Cymothoa elegans is a species of parasitic isopod in the genus Cymothoa. It has rarely been recorded, with all records coming from the north coast of Java. They are in the arthropod phylum and can more closely be classified as crustaceans.
Saltwater aquaponics is a combination of plant cultivation and fish rearing, systems with similarities to standard aquaponics, except that it uses saltwater instead of the more commonly used freshwater. In some instances, this may be diluted saltwater. The concept is being researched as a sustainable way to eliminate the stresses that are put on local environments by conventional fish farming practices who expel wastewater into the coastal zones, all while creating complementary crops.
Anilocra pomacentri is a species of marine isopod in the family Cymothoidae. It is found off the coast of eastern Australia and is an external parasite of the yellowback puller, a species of damselfish. The presence of the parasite on a fish causes a significant slowing of the growth rate and an increased mortality.
Amyloodinium ocellatum is a cosmopolitan ectoparasite dinoflagellate of numerous aquatic organisms living in brackish and seawater environments. The dinoflagellate is endemic in temperate and tropical areas, and is capable of successfully adapting to a variety of different environments and to a great number of hosts, having been identified in four phyla of aquatic organisms: Chordata, Arthropoda, Mollusca and Platyhelminthes. Moreover, it is the only dinoflagellate capable of infecting teleosts and elasmobranchs.
Tenacibaculum is a Gram-negative and motile bacterial genus from the family of Flavobacteriaceae.
Miamiensis avidus is a species of unicellular marine eukaryote that is a parasite of many different types of fish. It is one of several organisms known to cause the fish disease scuticociliatosis and is considered an economically significant pathogen of farmed fish. M. avidus is believed to be the cause of a 2017 die-off of fish and sharks in the San Francisco Bay.
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Enteromyxum leei is a species of myxozoan, histozoic parasite that infects the intestinal tract and sometimes associated organs, like gall bladder and liver, of several teleostean fish species. Myxozoans are microscopic metazoans, with an obligate parasitic life-style. The parasite stages of this species live in the paracelullar space between fish enterocytes. It is the causative agent of enteromyxosis, or emaciative disease, also known as "razor blade syndrome" in sparid fish. E. leei has a wide host and geographical range within marine fish, and even freshwater fish have been infected experimentally. E. leei initially emerged in the Mediterranean in the late 1980s and it is believed to have been unintentionally introduced into the Red Sea. Its pathogenicity and economic impact depend on the host species. In the gilt-head seabream, it is manifested as a chronic disease that provokes anorexia, delayed growth with weight loss, cachexia, reduced marketability and increased mortality. In other species, it has no clinical signs. In sharpsnout seabream, infection results in very high mortality rates, which have pushed fish farmers to abandon the culture of this fish species.
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