Fish Hatchery Management - fisheries & aquaculture

I.'ISH HEALI H MANACEMI.NT 333the intermediate host snails. In most cases, however, blood flukes are debilitatingbut not the cause of serious losses of fish. It is conceivable thatlarge numbers of miracidia leaving the gill at one time could cause a significantloss of blood and damage to the gills. Eggs and developing miracidiaalso interfere with the circulation of blood in the gill capillaries and in thecapillary beds of the kidney and liver.Copepod ParasitesMost copepods in fresh and salt water are an important part of the normaldiet of fish. Certain species, however, are parasitic on fish and the sites oftheir attachment may become ulcerated and provide access for secondaryinfections by fungi and bacteria. Crowded hatchery rearing units provideideal conditions for infestations by copepods because of the dense fish populationsand rich environmental conditions. Under most hatchery conditions,however, serious losses of fish seldom are caused by parasiticcopepods. The stocking of copepod-infested fish has infected wild fish instreams..s$a:, ,$t# Px{'.'*'.oGilY,\*tL *Jary',,,*-.Wrd.3i{..'!i":.,all.,sbJl&trTwfi8ri::s''ii _..,&. -t r "rtrt:;'#s1'"f.l:e lW;. ffu#,,t€'.&:.$,',,*',.;,,,{'l' **!':!.ry,,fq. '''''''';{...r: -.r...4 ..,rk ullii' ie. -sd tf-i; -sl ._*FIcunE 103. Sanguinicola daztisi,2,000x magnification. (Courtesy G. L. Hoffman,Fish Farming Experimental Station, Stuttgart, Arkansas.)