The process of transferring individuals of a species to a reservoir where the environmental conditions are slightly different from those of the species in the parent reservoir. There is no internal restructuring of the body. Fishes reproduce successfully in a new habitat without any prior internal restructuring of the body. The biological characteristics of the offspring of translocated fish do not change.

Acclimatisation is the process by which individuals of a species that have been moved to another pond adapt to a new environment in which their offspring form the population. This process is slow and involves profound restructuring of the body. The biological characteristics of successive generations of the species change.

Naturalisation - the final, highest stage of acclimatisation, when the species range in the new reservoir, its relationship with the environment and the ability to use the invader (food and commercial) are determined.