Fish habitat

Classification of waters or sections of water: No fish habitat are sections of water that cannot be permanently populated by fish. Potential fish habitats are sections of flowing waters that have not been accessible for fish from a river but can form a self-sustaining stock through stocking (i.e. initial stocking). Natural fish habitats are waters or sections of water that, around the middle of the 19th century, could allow the expression of a water type-specific, self-sustaining fish stock without human intervention.