Biology of the Copepod Ergasilus ogawai Kabata , 1992 Parasitic on Gills of Silurus triostegus at Garmat Ali River, North of Basrah City

Abstract

During  the period from  September  1999 till  August  2000, a

tota l  of 194 catfish Silurus triostegus were collected from Garmat Ali river,    orth of Basrah city. Heavy infestation with Ergasilus ogawai was  recorded  on  the  gills  of  S.  triostegus  with  an  incidence  of infection approaching  98.9% while the average intensity of infection was 417. The highest intensity recorded was 1985.

The size of parasites and the shape of its cephalothorax and ovaries  changed according to the age. The monthly observations  on egg  production   indicated  multibreeding   with  two  main  breeding seasons: spring and autumn. Preliminary laboratory study revealed the yield of nauplius I and  nauplius II larval stages from hatching of eggs in petri dishes. This copepod pierces its claws in the gill filaments of the host. It feeds on blood, gill tissues and body fluids.