国外精美的鱼类鱼病学PPT.ppt

I. Copepod parasites Argulus External, fish lice primarily a pond problem visible, flat, move about 2 sucking disks for attachment Pierce skin with mouthpiece and feed on blood. Large number vs. small number Secondary infections occur Lernea Slender copepods with anchor attachment (5-22mm) anchor causes tissue damage Secondary infection Lernea Easily identified Primarily warmwater fish Egg sacs are very obvious Ergasilus External Small (1.5 - 2.5 mm) Gill parasite Many fish species Actheres ambloplitis External Common on catfish Gill parasite Attach by leg like structures Egg sacs Especially bad on larval fish II. Trematode parasites Gyrodactylus External, visible Monogenetic (complete life cycle on fish) Live young - move readily No eye spots Haptor with 1 large pair of hooks and 16 hooklets Skin irritation but also on gills and fins Signs are listlessness, frayed fins, flashing, fungus Heaviest in winter and spring Dactylogyrus Monogenetic Lay eggs in water (not as explosive as Gyro) 4 eyespots 1 pair hooks, 16 hooklets Dactylogyrus Primarily a gill parasite So cause gill damage and symptoms can be mistaken for O2 problem or other gill infections Primarily warmwater, especially cyprinids Cleidodicus External, monogentic Eyespots 4 large anchor hooks Lay eggs On gills is problem Symptoms looks like O2 problem Warmwater fish, especially catfish Digenetic trematodes Quite a number are problems Some internal, some external Require more than 1 animal host Sanquinicola in salmonids blood fluke snails are intermediates Digenetic trematodes Various types of yellow and black grubs common in wild but in ponds also aesthetic problem only dont know why not in text snail - fish - bird cycle III. Protozoa I. multifilis Large ciliated protozoan Primarily ww fishes but some cw White color with large horseshoe shaped nucleus Flash, twitch, flag Heavily infested fish are lethargic Skin, gills, fins - penetrate skin so not exactly external Can be explosive since 1,000 or more from