The 1997-1998 El Nino event was characterized by rapid develop- ment, strength, and record high sea-surface temperatures in the eastern equatorial Pacific. Mobile organisms such as fishes with a tropical distribution showed a shift northward reaching high latitudes. Bahia de San Quintin is a coastal lagoon in north Pacific, Baja California, Mexico. Low temperatures caused by almost permanent upwelling, keeps lagoon temperature relatively low. However, the pres- ence of four tropical fish species in this lagoon during the seasonal sampling of 1998 indicated an influence of a string El Nino event. The bigscale goatfish (Pseu- dupeneus grandisquamis), the white grunt (Haemulopsis leuciscus), the bullseye puffer (Sphoeroides annulatus), and the paloma pompano (Trachinotus paitensis) are species of tropical affinity that were present in this coastal lagoon.