Abstract
Massive migration of Astyanax fasciatus in the Río Tempisque, Costa Rica, is reported roc the first time. Upstream movements begin about two weeks after the end of the rainy season, and continue for approximately one month. Observations were made in the Río Tempisque proper, but the phenomenon also occurs in several rivers on the Nicoya Peninsula. Migratory individuals were young, with undeveloped gonads. Population pressure and a consequent increase in competition roc road due to the reduction of aquatic habitat is proposed as the cause for migration.References
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Copyright (c) 1978 Revista de Biología Tropical