The pacu Piaractus mesopotamicus (Holmberg, 1887), is a commercially important serrasalmid fish endemic to the Paraná-Paraguay River basin, and one of the most widely cultivated native fish species in the Neotropics. As a migratory species, also inhabiting temporary pools subjected to hypoxic conditions, the species presents a high plasticity concerning respiratory adaptations. In order to supp...

The purpose of this work was to assess the quality of pacu (Piaractus mesopotamicus) and tambaqui (Colossoma macropomum) gutted and stored on ice for a period of 19 days. Color, texture, pH, acid value, peroxide value, thiobarbituric acid reactive substances, total volatile bases and counts of aerobic mesophilic heterotrophic and psychrotrophic bacteria assessments were performed in the meat of...

The levels of testosterone (T) and 11-ketotestosterone (11-KT) of the South American pacu Piaractus mesopotamicus were determined by radioimmunoassay during two stages of the reproductive cycle, i.e., resting and maturation, and the gonadosomatic index (GSI) was calculated. The highest levels of T and 11-KT were reached during the maturation stage (T = 2400 +/- 56 pg/ml; 11-KT = 2300 +/- 60 pg/...

An investigation of the histological and ultrastructural changes of Sertoli cells during the male reproductive cycle in Piaractus mesopotamicus was made. The results showed that the Sertoli cell development is closely related with germ cell maturation. Therefore, these cells may have some role in germ cell maturation during the reproductive cycle of this species, whether in forming a tissue fra...

Innate immune responses are useful to determine the health status of fish and to evaluate the effect of immunomodulatory substances in fish farming. Leukocytes respiratory burst was measured in pacu (Piaractus mesopotamicus) using chemiluminescence assay and nitroblue tetrazolium (NBT) reduction assay. The nitroblue tetrazolium reduction seemed more adequate than chemiluminescence assay for leu...

Analysis of mitochondrial cytochrome b sequences from 198 species confirms the position of Barilius mesopotamicus as a species of the Asian genus Barilius within the subtribe Chedrina in the subfamily Danioninae. This relationship is supported by a parsimony analysis based on 43 morphological characters, and the morphological examination confirms that B. mesopotamicus possesses the synapomorphi...