parasitic copepods are responsible for a massive mortality of stocks, however, there has been a lack of knowledge on the Algerian freshwater fish. Therefore, the present work aimed to study the infestation of copepod ectoparasites of 499 fish, including 257 individuals of Luciobarbus callensis (Valencienne ,1842) and 242 of Carassius carassius (Linnaeus, 1758) species found in Beni Haroun Dam (Mila, Algeria). The fish were subjected to some morphometric measurements, and thereby, a gill dissection was measured, harvested, preserved and identified, as well the parasitic indices were calculated. The effect of some parameters (size, sex season, and microhabitat) on the parasite infestation was tested by using test. The gill examination of the individuals of the two host populations led to an inventory of eight parasitic species in Luciobarbus callensis and six species in Carassius carassius. Also, the study of epidemiologic indices of host species revealed that the higher recorded values were found in Luciobarbus callensis (P= 12,84%; I=2.33; A=0.29) (Tab.1). Nevertheless, the seasonal evaluation of the parasite indices of copepods obtained from the same species revealed that the most important values were noted in summer (P=23,63%; A=0,61; I=2,61). Moreover, Carassius carassius provided high infestation rates and parasite infestation charges, respectively during spring (I=1.77; A=0.21) and summer (P=12.76%). The c2 values showed the effect of season ( obs = 18.833 > 0.05 = 6.251 ddl=3) and the size ( obs =14,639 > 0,05 =4.605; ddl=2) on the parasite infestation of the two host species, since there was no effect due to the microhabitat and sex.
