Occurrence of parasites of the freshwater mugilid fish Liza abu (Heckel) from Basrah, southern Iraq

Abstract

In monthly samples of Liza abu collected November 1981–October 1982 from Mehaijeran Creek, a western branch of Shatt–Al–Arab river south of Basrah, fishes were infected with the third larval stage of the nematode Contracaecum sp., the acanthocephalan Neoechinorhynchus agilis and the gill crustacean Ergasilus mosulensis.Generally, the changes in the percentage prevalence coincided with the changes in the mean intensity of infection. There were no significant differences between the infection of male and female fishes in the cases of the monthly variations of infection with Contracaecum sp. and of infection with both Contracaecum sp. and E. mosulensis, according to fish length, but in other cases more female fishes were infected than males.Infection with Contracaecum sp. decreased gradually in the larger fishes. In the case of both N. agilis and E. mosulensis, the infection at first increased with increase in fish length but decreased in larger fishes.Infection with Contracaecum sp. occurred only during May–August and disappeared during September. The peak for N. agilis was in April, and it disappeared during summer. Infection with E. mosulensis disappeared during winter months.