Fish-parasite

Guides

• Aegidae

  aegid isopods

  Aegidae is a family of marine and freshwater isopod crustaceans characterized by temporary parasitic relationships with fish hosts. Adults attach to hosts to feed on blood or tissue, then detach to digest meals. The family is distinguished from related Cirolanidae by having only three pairs of hook-like pereiopods rather than seven. Members occur in diverse aquatic habitats from shallow coastal waters to deep ocean environments, with some species documented at depths exceeding 2000 meters.

  parasitefish-parasitetemporary-parasiteisopodcrustaceanaquaculture-pestmarinefreshwaterdeep-seaectoparasite

• Anilocra

  Fish Lice

  Anilocra is a genus of marine isopods in the family Cymothoidae, commonly known as fish lice. Members are obligate external parasites of teleost fishes, attaching to host skin and feeding on blood. The genus exhibits sequential hermaphroditism, with individuals beginning life as males and transitioning to females as they grow. Parasitism by Anilocra species has been documented to reduce host growth rates, fecundity, and survival.

  parasitemarinecymothoidfish-parasitehematophagoushermaphroditecoral-reef

• Arguloida

  Fish Lice

  Arguloida is an order of parasitic crustaceans commonly known as fish lice. The order contains a single family, Argulidae, whose members are obligate ectoparasites of freshwater and marine fishes. These organisms have an uncertain phylogenetic position within Maxillopoda and lack any known fossil record. They are distributed globally across temperate and tropical waters.

  parasitefish-parasiteaquaculture-pestectoparasitecrustacean

• Argulus

  Fish Lice, Carp Lice

  Argulus is a genus of ectoparasitic crustaceans commonly known as fish lice, comprising approximately 130–140 accepted species. They are obligate parasites of fish, inhabiting marine, brackish, and freshwater environments worldwide. The genus exhibits low host specificity and can infest diverse fish species, with documented impacts on host health including immunosuppression and facilitation of secondary bacterial infections.

  ectoparasitefish-parasiteaquaculture-pestBranchiuracrustacean

• Branchiura

  Branchiurans, Fish lice

  Branchiura is a subclass of crustaceans within the class Ichthyostraca, comprising approximately 170 species of ectoparasitic fish lice. The group contains two extant families: Argulidae (fish lice) and Chonopeltidae, plus the extinct Cyclida. Branchiurans are obligate ectoparasites of freshwater and marine fishes, characterized by a flattened body adapted for clinging to host surfaces and specialized mouthparts for feeding on host blood, mucus, and tissues.

  ectoparasitefish-parasiteaquaculture-pestcrustaceanArgulidae

• Elthusa

  Elthusa is a genus of cymothoid isopods comprising approximately 40 described species of obligate fish parasites. Species in this genus are characterized by branchial parasitism, attaching to the gill filaments of marine fish hosts where they feed on blood and tissue fluids. The genus has a worldwide distribution with records from the Atlantic, Indian, and Pacific Oceans. Several species have been described from South Africa, New Caledonia, Taiwan, and Japan, with some exhibiting host specificity while others parasitize multiple fish species.

  isopodcymothoidfish-parasitebranchial-parasitemarinehematophagouscosmopolitan-distribution

• Elthusa californica

  Elthusa californica is a marine parasitic isopod in the family Cymothoidae. It attaches to the gill chambers of fish hosts and feeds on blood and tissue. The species occurs along the Pacific coast from California to Peru. Originally described as Lironeca californica, it was later transferred to Elthusa following taxonomic revision.

  marineparasiteisopodcymothoidfish-parasitePacific-coastectoparasitegill-parasitehybridizationindicator-species

• Heterocheilidae

  half-bridge flies

  Heterocheilidae is a family of parasitic nematodes (phylum Nematoda) within the order Rhabditida and infraorder Ascaridomorpha. Members are intestinal parasites primarily infecting fish hosts, including elasmobranchs and teleosts. The family includes genera such as Brevimulticaecum, Ortleppascaris, and Dujardinascaris. Notably, the name 'Heterocheilidae' has also been applied to a family of dipteran insects (true flies), but this usage is taxonomically distinct and not accepted in current nematode classification.

  parasitenematodefish-parasiteintestinal-parasiteascaridomorphelasmobranch-parasitefreshwatermarineaquaculturemitochondrial-genomemolecular-phylogeny

• Lernaeopodidae

  Lernaeopodidae is a family of parasitic copepods in the order Siphonostomatoida. Females are typically large and fleshy, attaching permanently to fish hosts using a chitinous plug called the bulla. Males are smaller and cling to females using their antennae. Members parasitize both marine and freshwater fishes, with some species causing significant problems in aquaculture.

  parasitecopepodfish-parasiteaquaculture-pestbullapermanent-attachmentsexual-dimorphismmarinefreshwater

• Siphonostomatoida

  Siphon-mouth Copepods

  Siphonostomatoida is an order of copepods distinguished by siphon-like mandibles and a frontal filament used for host attachment. The order comprises 40 recognized families, with approximately 75% of all fish-parasitizing copepods belonging to this group. Most species are marine symbionts, though a few inhabit freshwater environments. Members exhibit diverse host associations, with 17 families parasitizing vertebrates (primarily fishes) and 23 families associated with invertebrates.

  copepodparasitemarinefish-parasitesymbiontcrustaceanectoparasiteSiphonostomatoidabiodiversitySouthern-AfricaJapanBrazilsponge-associatecoral-associatedevelopmental-stageschalimusfrontal-filamentsiphon-mandibleAsterocheridaeLernaeopodidaePennellidaeHatschekiidaeSphyriidaeNotodelphyidaeBotryllophilidae