In 1958, black bass were introduced into Lake Atitlan in the highlands of western Guatemala as a way to attract tourism and boost the local economy, but unforeseen complications resulted in an ecological disaster. Developed for an introductory course in biology, this case study first casts students in the role of the local population at that time and asks them to judge the proposal to introduce the new species of fish. The students then review the ensuing events from a historical perspective based on additional information they receive from the instructor in a progressive disclosure format.