| The construction of the Itaipu Hydroelectric Power Plant in 1982 led to the formation of a reservoir, which, in turn, leveled the waters of the Paraná River by flooding the geographic barrier Salto de Sete Quedas. This allowed the piranha Serrasalmus marginatus to invade and colonize the upper Paraná River. This study aimed to: i) confirm, through light microscopy, the reproductive phases of S. marginatus females; ii) estimate fecundity and iii) evaluate the reproduction areas of the population. A total of 764 females were collected from nine sampling sites on the upper Paraná River floodplain. Microscopic analysis of the ovaries showed the following phases: early developing subphase, developing phase, spawning capable phase, actively spawning subphase,... |
