Manipulative Strategies of Aquatic Arthropods for Fish Parasitism: A Review

Abstract

Several aquatic arthropodan classes, including Arachnida, Crustacea, and Ostracoda can parasitize on fish and might cause discomfort or serious harm to their tissues. These organisms can parasitize fish through either obligatory, facultative, or opportunistic relationships according to their behavior or the surrounding conditions. Free-living arthropods may be induced to parasitize fish by various physiological, environmental, or biological stimuli. Some other non-fish parasites can switch their behavior towards fish parasitism. On one hand, members of both Classes Arachnida and Ostracoda are free-living and may exhibit opportunistic parasitism of fish through nocturnal predation or attacking weakened or captivated fish. On the other hand, Class: Crustacea is wide and comprises true fish parasites, non-fish parasites, and non-parasitic forms included in three Orders: Isopoda, Branchiura, and Copepoda. Isopods are efficient attackers targeting fish body surfaces, buccal cavities, and muscles through hydrodynamic impairment, sneaking as couples, and flesh-burrowing strategies. Branchiurans are true ectoparasites having well-developed senses for host localization and then follow a physiological strategy of injecting fish with toxic digestive fluids. When it comes to fish parasitic copepods, they are either females with robust structural features for infesting fish bodies or tiny-sized individuals capable of fish endo-parasitism by sneaking inside. Notably, the free-living and the non-fish parasitic crustaceans might be forced to parasitize fish facultatively, transitory, or occasionally. Parasitic and predatory arthropods possess structural facilities besides employing behavioral tactics for handling fish bodies successfully. The current manuscript surveyed the different strategies and unusual environmental conditions that facilitate fish parasitism by the aquatic Arthropods.