This is the eleventh technical paper on water quality criteria for European freshwater fish, for the European Inland. Fisheries Advisory Commission (EIFAC) - an inter-governmental organization with a membership of 23 countries. The Commission has been active in its efforts to establish water quality- criteria for European freshwater fish since its Second Session, Paris, 1962, when it took note of a recommendation of the United Nations Conference on Water Pollution Problems in Europe, 1961, that EIPAC take the initiative in drawing up water quality requirements with respect to fisheries.