Biofouling is usually defined as an especially economically significant process that occurs on ships' hulls, where high levels of fouling can reduce the performance of the vessel and increase its fuel requirements. However, in the aquatic environment, such burden is generally of importance for all types of organisms present. This book concentrates on aquatic mammals from marine and freshwater biotopes, summarising their different strategies to cope with the permanent challenge of being colonised by a multitude of bacteria, fungi or algae, and moreover, larvae of different invertebrates. Furthermore, biofouling of medical devices involves the formation of a biofilm by bacteria. This book covers the recent advances on the main anti-biofouling strategies based on the application of emergent biological products. In addition, the authors of this book focus on the surface modification of membranes for antibiofouling. The effect of non-antibiotic pharmaceuticals on the growth and adhesion of marine bacteria found in biofilms is looked at. Finally, in order to produce antifouling paints with reduced amount of toxic molecules, it is necessary to further investigate the phenomena involved in antifouling activity.