Wikipedia
Piracema
Piracema (from tupi "pirá", fish + "sema", exit) is the name given to the period of the year when fish within the Paraguay River drainage basin―which includes the Pantanal region in the Brazilian states of Mato Grosso and Mato Grosso do Sul―reproduce.
The season lasts from October to March, during which the fish swim upstream to lay their eggs and reproduce. Thus the season is critical for the maintenance of fish populations in the waters of the local rivers and lakes. Both of the Brazilian states prohibit fishing during this period.