Variations in fat content of the Peruvian anchovy after "El Niño" phenomenon (July 1998-August 1999) are presented confirming the correlation between fat content and spawning of fish as a consequence of this natural disruption. Results obtained show extremely low values (fat content of 0.91% in July 1998). A gradual recovery of the species to normal values of 11.20% was observed in June 1999. © 2002 Published by Elsevier Science Ltd.