Larvae of Porrocaecum sp. (Nematoda: Ascarididae) in the swim bladder of cultured Piaractus mesopotamicus (Osteichthyes: Characidae) in Brazil

Abstract

This work describes the presence of larvae of Porrocaecum sp. (Nematoda: Ascarididae) in the swim bladder of pacu, Piaractus mesopotamicus (Osteichthyes: Characidae) cultivated in Uberaba, Minas Gerais State, Brazil. Thirty fish measuring 11.9 ± 0.7 cm total length and weighting 34.3 ± 6.2 g were examined. After sedation, blood smears for differential count of leukocytes were performed. Seventeen percent of prevalence with a mean intensity of 10 (1-36) parasites per host was the data of infection. The larvae showed differences in the length of esophagus and intestinal caecum, distance of excretory pore from anterior end and tail when compared to Porrocaecum reticulatum, P. crassum, P. semiteres and P. ensicaudatum larvae. The blood smears were composed mainly by lymphocytes and no difference between infected and healthy fish was related. This work contributes to knowledge of helminth fauna in Brazilian cultivated fish and presents a new host for larvae of Porrocaecum sp.