Abstract
During a survey of the helminth parasites of fresh water fishes in Willamette River, metacercariae of Neascus spp. were found on examination of muscle, spinal cord, fin and skin of Chiselmouth, Acrocheilus alutaceus. One hundred percent of 19 Chiselmouth examined were found to be infected with digenetic trematodes. The prevalence of infection was higher in muscle, varying from $95\%\;and\;100\%$. Higher levels were present in muscle, such that the $100\%$ level being found in upper anterior, lower anterior and posterior. Small numbers of metacercariae were found on the fin and skin. The commonest sites of infection were the musculature and spinal cord. Intensities of Neascus spp. metacercariae tended to be and high levels in muscle and spinal cord. Those were low levels occurred in the fin and skin. There was a high degree of Neascus spp. in the occurrence of digenetic trematode from Chiselmouth.