[The distribution of Lernaea cyprinacea (Copepoda: Lernaeidae) in a crucian carp population].

Differences in the infection with copepods and the character of distribution of occurrence frequencies of Lernaea in crucian carp depending on the body length and sex of the latter are shown. The lowest infection rate with copepods was recorded for fishes with body length 8-11 cm as compared to specimens with body length 12-18 and 18.5-34 cm. The two latter groups did not differ from each other in this index. In males and females whose body length is 8-11 cm as well as in females with body length 12-34 cm the occurrence frequencies of Lernaea are satisfactorily described by the negative binomial distribution curve. In males with body length 12-18 cm the occurrence frequencies of copepods are approximated by the binomial distribution curve. On the basis of obtained data it was concluded that fishes with a small body length as well as Carassius males and females with a greater body length represent three distinct host groups which differ in their part of maintaining the number of Lernaea of the host group.