The yellowtail kingfish Seriola lalandi is one of the most important fish candidates for the diversification of aquaculture in Chile. Fish farmed experimentally in one floating cage on a site located in Northern Chile, between November 2013 and December 2015, were first detected with the sea lice Caligus lalandei from April 2014. The highest prevalence (100%) was reached in July 2014 and the highest abundance in June 2014 (4.3 lice/fish). The monogenean Benedenia seriolae was also recorded in the same stock of fish from July 2014, reaching the highest abundance of 30.8 parasite/fish and a prevalence of 100% in January 2015. When the abundance of B. seriolae increased, C. lalandei abundance decreased until it disappeared in January 2015, which could be attributed to the increase of the seawater temperature in the period of study. This is the first report of C. lalandei infecting S. lalandi reared in net cage in Chile.