Aquaculture-pest
Guides
Acanthocephala
thorny-headed worms, spiny-headed worms, acanthocephalans
Acanthocephala is a phylum of obligate endoparasitic worms known as thorny-headed or spiny-headed worms, characterized by an eversible proboscis armed with recurved hooks used to attach to host intestinal walls. They lack a mouth and digestive system, absorbing nutrients directly through their tegument. The phylum contains approximately 1,200–1,420 described species with complex life cycles involving arthropod intermediate hosts and vertebrate definitive hosts. Recent molecular evidence indicates they are highly modified rotifers, now sometimes classified within Syndermata or Rotifera.
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.
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.
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.
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.
Caprella mutica
Japanese Skeleton Shrimp
Caprella mutica is a highly invasive caprellid amphipod native to the Sea of Japan. It has spread to temperate coastlines worldwide through maritime shipping and aquaculture, becoming established in the North Atlantic, North Pacific, New Zealand, and most recently South America. The species exhibits pronounced sexual dimorphism, with males reaching 50 mm and females averaging 15–20 mm. It is characterized by densely setose first and second pereonites in males and remarkable ecological plasticity, enabling dense populations on artificial structures.
Lernaea
anchor worms
Lernaea is a genus of parasitic copepod crustaceans commonly called anchor worms, exclusively parasitic on freshwater fishes. Females burrow into fish flesh and transform into unsegmented, wormlike forms with egg sacs visible externally, while males are free-swimming and short-lived. The genus is widely distributed globally and causes significant disease in aquaculture and wild fish populations. Multiple species exist, with Lernaea cyprinacea being the most studied and economically important.
Lernaea cyprinacea
anchor worm, fish louse
Lernaea cyprinacea is a parasitic copepod commonly known as the anchor worm, a significant pest in freshwater aquaculture worldwide. Native to Eurasia, it has been introduced to multiple continents including North America and South America. The species exhibits sexual dimorphism with females becoming permanently attached to fish hosts while males are free-living and short-lived. It causes substantial economic damage through direct parasitism, reduced fish growth, and secondary infections.
Lernaeidae
anchorworms
Lernaeidae is a family of parasitic copepods in the order Cyclopoida, commonly known as anchorworms. The family contains approximately 131 species across 20 genera, all of which are obligate ectoparasites of freshwater fishes. Species in this family are characterized by elongated bodies, often with anchor-like holdfast structures used for attachment to host tissues. The most widely distributed and economically significant species is Lernaea cyprinacea, which has been introduced globally and causes substantial damage in aquaculture systems.
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.