STUDIES ON SKIN PARASITIC DISEASES AMONG CULTURED OREOCHROMUS NILOTICUS FISH

Abstract

The present study was carried out on 450 alive specimens of Oreoc!Jromis niloticus of different size and body w1:1ght were randoml y collected from a special fish farm in Dakahlia Governorate for the detection of the skin parasitic dtseases during dif(erent seasons. Clinical signs and postmortem leswns of 0 niloticus infested with ciliated protozoa revealed skin coloration with excessive outer shmy layer, small blood spots were detected at the base of fins, skin and scale detachment, also the skin of O.niloticus infested with monogenetic trematode revealed sluggish movement, loss of appetite, exc :ssive mucuus secretion hemorrhagic skin & scale detached, Ji·ayed fins, emaciation. The isolated parasites obtained from examined fishes were ciliated protozoa including Tric!Jodina sp.. C/iilodonella 5p.. Scyphidia sp., and Apiosoma (G/ossatella sp.). flagellated protozoa including lcht!Jyobodo necator, monogenetic trematodes inclued Gyrodacly/us sp., mixed monogenea and protozoa. The total prevalence of skin parasitic infestation in O.ni/olicus was 63.3%. The results indicated that the infestation rates with Tric!Jodina sp., C!Jilodonel/a sp., Scvpllidia sp. , Apiosoma sp., !chthyobodo necator, Gyrodacty/us sp.. Cruswcea and Mixed monogenea & protozoa were 20.7%, 8.9%, 13.8%, 3.3%, 2.9%, 7.8%, 0% and 6% respectively. Seasonal ncidence of extemal parasites from examined Oni/oticus revealed that Trichoclina sp. reached its highest rate of infestation during autumn (26. 7%) while the lowest rate was during summer 13.3%, Chilodone/la sp., reached its bighest rate of infestation during autumn 14.7% and was not found during summer, Scyphic:ia sp., reached its highest rate of infestation during autunm 17.3% and spring 14% while Apiosoma (Glossatells sp.) reached i[s highest infestation in Autunm 4.7%. Ichthyobodo necator recorded only in autunm with a rate of 8.7%. also Gyrodactylus sp. reached high prevalence in Autumn 13.3%. It was noticed that mixed infestation with protozoa and monogenea were reached its maximum infestation in autumn 10% than spring 8% but n:>t recorded in summer. 1i'ichodina sp., Chilodonel/a sp., Scyphidia sp., and Apiosoma (Glossa/ella sp) showed htgher prevalence of infestation on the skin 64.5%, 72.5% 6-1.5% and 80% respectively. But !chthyobodo necator & Monogenea (Gyrodactylus sp) >hawed higher prevalence of infestation on the fins 61.5% and 57.1% respectively.