There is a clear relationship between the way understand a phenomenon and how we act about it, and this is especially important when working with environmental subjects. Environmental problems are often abstract or imperceptible to students and for this reason difficult to understand. This article is part of a more detailed study on how trainee teachers use ecological knowledge when dealing with particular environmental issues. This paper reports on the results of using a multimedia application, an interactive CD-ROM about fishing, with trainee teachers. The use of the interactive tool on an autonomous way has been reasonably successful for the students, who have reacted positively when allowed to work on their own individually or collectively. The students are able to answer correctly to the simplest aspects of the descriptive and explicative fields within the ecological models. On the other hand, the majority of the students do not fulfil the argumentative and applicative aspects of the knowledge due to the lack of basic elements that allow them to achieve the following competences: identify the model elements, identify and tell rightly the interrelations between them, connect causes and consequences.