SummarySufficient and adequate direction of flows for maintaining historically-present native fish. Native fish are often adapted to certain hydrologic regimes and may not tolerate modified flow patterns or quantities. General Information about this IndicatorWhat is it?: Native fish are often adapted to certain hydrologic regimes and may not tolerate modified flow patterns or quantities. In estuarine systems, both sufficient water and (bi)directional flow may be important. In stream and river systems, insufficient flows to maintain native fish may occur due to over-subscription of surface and ground water, as well as reduced precipitation from climate change.