Aquaculture production is increasing rapidly as modern techniques are applied to an expanding range of species. One particular adverse consequence of aquaculture is the impact of interactions between the organism under culture, which is often both exotic and invasive by nature, and the indigenous biota of the surrounding environment. Species interactions due to aquaculture activities may result from the attraction of local biota to culture facilities, of the escape of cultured organisms, their diseases or parasites into the environment. The effects of species interactions can be classified as: disturbance of the local aquatic environment, disturbance of the surrounding biotic community, genetic degradation of indigenous stock, and the introduction of diseases and parasites. Drawing on the aquaculture experiences of developed and developing countries, this paper reviews the various types of species interactions and their effects on the local environment. These issues are discussed in terms of direct ecological effects and the human perspectives (management, government, local community) pertaining to the various culture systems, Examples are drawn from aquaculture activities in a range of habitats (freshwater, brackish water, marine), culture systems (intensive, semi-intensive, extensive), and culture facilities (cages, pens, ponds). Approaches to the management of invasive species are outlined.