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Like humans and other animals, fish suffer from diseases and parasites. Fish defences against disease are specific and non-specific. Fish defences against disease are specific and non-specific. Non-specific defences include skin and scales, as well as the mucus layer secreted by the epidermis that traps microorganisms and inhibits their growth.
VHS disease in a gizzard shad. Viral hemorrhagic septicemia (VHS) is a deadly infectious fish disease caused by Viral hemorrhagic septicemia virus. It afflicts over 50 species of freshwater and marine fish in several parts of the Northern Hemisphere. [1] Different strains of the virus occur in different regions, and affect different species.
Edwardsiella ictaluri (also known as enteric septicaemia of catfish, hole in the head disease [2] and ESC) is a member of the family Hafniaceae. The bacterium is a short, gram negative , pleomorphic rod with flagella.
Edwardsiella tarda is a member of the family Hafniaceae. [1] [2] The bacterium is a facultatively anaerobic, small, motile, gram negative, straight rod with flagella.[1] [2] Infection causes Edwardsiella septicemia (also known as ES, edwardsiellosis, emphysematous putrefactive disease of catfish, fish gangrene, and red disease) in channel catfish, eels, and flounder.
It is visible as a white spot on the surface of the fish but, due to its internal microhabitat, it is a true endoparasite and not an ectoparasite. [3] It causes a disease commonly referred to as white spot disease due to the macroscopically visible trophonts (up to 1 mm in diameter) in the skin and fins.
Very little research on the human health effects of Pfiesteria toxins has been conducted. At a multi-state workshop at the Centers for Disease Control and Prevention (CDC) in Atlanta , U.S. , at the end of September 1997, attendees agreed on clinical symptoms that characterize a new illness associated with Pfiesteria exposure.
HLLE begins as small pits of receding epithelium (skin) around the fish's head and/or lateral line, and sometimes onto the unpaired fins. Rarely fatal, it does cause disfigurement, making the fish less suitable for public aquarium display. At least 20 families of fish have been identified as having developed HLLE in captivity.
The infected fish also becomes lethargic, swims near the surface, and its appetite decreases. [10] Additionally the infected fish may hold its gill covers open and scratch its gills on rocks. [14] In severe infections, Dactylogyrus species can cause hemorrhaging and metaplasia of the gills which can lead to secondary bacterial infections and ...