Barramundi Lates calcarifer is one of the leading marine aquaculture commodities in Indonesia, therefore fish health should be observed. This study was conducted to determine the type and number of parasites present in barramundi, the prevalence, mean intensity and mean abundance of parasite and the number of leukocytes in each individual, based on the level of infestation. This study used a quantitative descriptive method, using a total of 30 fish with two different sizes of host of ± 20 cm (large) and ±5 cm (small) each as many as 15 individuals. The results showed that size of host samples influenced the number of parasites infested with the prevalence of 40%, while ectoparasite 20%. This may due to differences in the living environment as well as the larger host provides more space to the parasites. The ectoparasites found in barramundi, namely Trichodina sp, Cryptocaryon sp, Benedenia sp, Diplectanum sp and endoparasites, namely Camallanus sp. Ectoparasites Trichodina sp. has the highest mean intensity of 20%. The highest mean abundance on large fish was 3.2 ind/fish on ectoparasite and endoparasites was 0.07 ind/fish. The lowest leukocytes were 179.82 103/μl (19.6 cm) and the highest in sample number three was 218 103/μl (20 cm), all exceeded the normal amount of leucocytes cells for fish was uninfected.