Wildlife feeding has become an integral part of the range of activities offered to protected area visitors. In marine protected areas (MPAs), fish feeding may cause changes in the behavior, and thus the density and distribution, of coastal fish species. We evaluated spatial variability in human-positive fish behavior around the Ustica Island MPA (Italy) and the potential indirect effects of behavioral change on other species. Two mensurative experiments demonstrated that ca. 1/3 of the species present in fish-feeding areas exhibited human-positive behavior, losing instinctive fear in the presence of humans and encircling people in the water even when food was not provided. A manipulative experiment demonstrated that this behavioral response was learned rapidly. Damselfishes were negatively affected by the unnatural aggregation of a labrid species, as these aggregations frequently attacked and destroyed the benthic nests of the damselfish. Thus, fish feeding can have both direct and indirect effects. Therefore the MPA management goals need to be explicitly stated on a case-by-case basis. If the aim of a reserve is only to promote awareness of marine life and the benefits of conservation to the public, activities such as fish feeding may be regarded as desirable, since the human-positive behavior brought about by this activity guarantees a visual spectacle for visitors. Fish-feeding locations, however, cannot be regarded as natural and may reduce the effectiveness of a reserve for scientific research.