This study examined how weakly electric fish use landmarks to form an internal representation of their environment.  It was hypothesized that weakly electric fish would learn their environment faster with a landmark present than without, rely on water depth cues over landmark cues, and change their navigation path when landmark size was altered.  Eight Gnathonemus petersii were subjected to 10 training trials, landmark size and water depth cues were manipulated.  Results indicated that fish provided with landmarks learned to locate the aperture more quickly than fish with landmarks, they relied on water depth cues over landmark cues, and their navigation path was not significantly altered with a change in landmark size.