There is evidence for changes in the environment and therefore fish habitats during historical times. Many of these changes are man-made and are on-going. References to change, e.g. habitat loss, pollution, effects of exotic species, etc., can be found in each of the Drainage Basin files. This topic has been reviewed in general by Coad (1980c) and the references therein, with papers cited under Climate, are relevant.

Peritore (1999) gives a general overview of ecological conditions and attitudes to the environment, Foltz (2001) reviews environmental initiatives, Afasiabi (2003) reviews the environmental movement in Iran and Valeolahy (2000) reviews the factors affecting the abundance of fishes and suggests measures for conservation. Jawad (2003) gives an account of the impact of environmental change on Iraqi fishes which has implications for fishes in neighbouring waters of Iran.