Reproductive Activity of Spotted Metynnis Metynnis maculatus (Serrasalmidae), a Non-Native Species in the São Francisco Basin, Três Marias Reservoir, Minas Gerais, Brazil

Several non-native fish species can be found in the São Francisco River basin. One of the introduced species is the spotted metynnis or Pacu-CD (Metynnis maculatus), a Neotropical fish belonging to the Serrasalmidae, native to the Amazon River basin. We analyzed the main reproductive variables of M. maculatus. A total of 212 specimens (98 females and 114 males) of spotted metynnis were collected from the Três Marias reservoir between January and December, 2012. The fish were dissected for anatomical analysis of the gonads. Gonads were subjected to routine histological techniques. Macroscopic observation of the ovaries showed gonadal asymmetry, with the right ovary being larger than the left. The species reproduced according to a seasonality in the Três Marias region, and displayed batch spawning.