Productive areas are typically associated with specific types of structure. Confluences where smaller tributaries enter the main river often create current seams and deeper holes that concentrate fish. Areas with significant submerged timber, such as fallen trees and logjams, are prime holding water for Tucunaré and Traíra. Undercut banks, especially those shaded by overhanging vegetation, provide excellent ambush points. Deep pools located at the tail end of rapids or below riffles are always worth prospecting, as fish rest and feed in these transition zones.