The level and trend of the Danube waters have a big influence on fish behaviour. Taking into account that 55% of the Delta's surface is between 0 and 1 m above sea level, it is easy to understand why a fluctuation of 1 m can lead to the changing of the feeding area for the fish. These surfaces on which a rich vegetation grows, are periodically flooded and fish such as pike, carp or crucian feel very good in these places. During flood periods fish spread in the larger areas, while during draughty periods such as the summer they are forced to gather in the deeper areas in channels or lakes. The water trend is an other factor that changes fish behaviour. A low water level alerts fish and they begin to feed intensively while a high water level makes them less receptive at baits and more interested in new feeding places. But there are also moments where fish bite very good while the water level is rising, but generally it is good for the water level to go down.
A 100 cm elevation at Tulcea represents a draughty period for Danube Delta, while the 300 cm elevation represents a flood period (the water has covered the floodable areas and is quite deep 30-50 cm to permit fish to swim in. Therefore a difrence of water level of 100 cm at Tulcea represents aproximaively 30-40 cm in Caraorman, sensed in about 2 or 3 days. The higher the water level, the stronger the stream on the channels.

Danube level - Tulcea	Graph Danube level-Tulcea	Comments
15 mar. 2003 Tulcea 184 cm rise 14 cm
17 ian. 2003 Tulcea 301 cm rise 3 cm