![]() ![]() Evolutionary constraints may operate so parasites avoid killing their hosts, or the natural variability in host defensive strategies may suffice to keep host populations viable. Usually parasites (and pathogens) need to avoid killing their hosts, since extinct hosts can mean extinct parasites. Understanding these aspects of parasite ecology, of interest in their own right, can illuminate parasite-avoidance strategies employed by hosts. Additionally, parasites possess a variety of specialized traits and life-history strategies that enable them to colonize hosts. In fisheries biology, for example, parasite communities can be used to distinguish distinct populations of the same fish species co-inhabiting a region. Parasites can provide information about host population ecology. Parasites in fish are a common natural occurrence. Some commercially important fish diseases are VHS, ICH, and whirling disease.Īdult Siamese fighting fish ( Betta splendens) with velvet disease In recent years, vaccines have become widely used in aquaculture and ornamental fish, for example vaccines for comercial food fishes like Aeromonas salmonicida,furunculosis in salmon and Lactococcosis\Streptococcosis in farmed grey mullet, Tilapia and koi herpes virus in koi. Specific defences are specialised responses to particular pathogens recognised by the fish's body, that is adaptative immune responses. If pathogens breach these defences, fish can develop inflammatory responses that increase the flow of blood to infected areas and deliver white blood cells that attempt to destroy the pathogens. FRESHWATER FISH PARASITE IDENTIFICATION SKINNon-specific defences include skin and scales, as well as the mucus layer secreted by the epidermis that traps microorganisms and inhibits their growth. Fish defences against disease are specific and non-specific. Like humans and other animals, fish suffer from diseases and parasites. It is caused by a microsporidian fungal parasite in its intestines. This flatfish Limanda limanda has an outgrowth called a xenoma. ![]()
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