Fish Hatchery Management - fisheries & aquaculture

FISH HATCHERY MANAGEMEN IFtcunE 95. Hexamita salmonis FIGURE 96. Hennegultasp.hexamitiasis must be made by microscopic examination of gut contentsfrom the anterior portion of the intestine and pyloric caeca. The flagellates(Figure 95) are minute, colorless, pear-shaped organisms that dart rapidlyin every direction. Gross signs of infected fish may include swimming in acork-screw pattern, and a dark emaciated condition commonly called"pin-headed." The protozoan may become abundant in fish that are fedmeat diets, and can cause irritation of the gut lining. With the advent ofprocessed diets, incidence of the disease has greatly declined.Therapy is not recommended nnless Hexamita salmonis is abundant. Fortreatment, leed epsom salt (magnesium sulfate) at the rate of 3nu of the dietfor2or3days.HENNEGUTASeventeen species of Henneguya have been described from a wide variety ofNorth American freshwater fishes. The following remarks are limited to therelationship of these parasites to hatchery-reared species, primarily channelcatfish.