We’ve really never made it easy for the fish residing in Berlin’s lakes and rivers. Waters were dammed up as early as the Middle Ages to operate mills, due to a sluggish water flow. From the 17th century onwards, ships could pass more easily as rivers were straightened. Dams and weirs built for that purpose now posed an insurmountable obstacle to migrating fish, however. When factories and sewage systems started discharging wastewater into the rivers Havel and Spree in the 19th century, many fish species were robbed of their habitat and spawning grounds. The pond lamprey, the vimba bream and the barbel became extinct.
With the slow improvement of the water quality due to growing environmental awareness, fish stocks have slowly been recovering, too. Most recently, an analysis of 153 of Berlin’s water bodies revealed the presence of 38 species of fish. The network of Havel lakes contains the largest number of fish species (31); the Rummelsburger See is the tail end with only six species. Particularly common species include the roach, the brusque and the pike. However, the rare loach, which had not been sighted since 1920, has meanwhile reappeared. Surveys from 1993, 2004 and 2013 reflect this positive development, too.
The legal conditions for the improvements were set by the European Water Framework Directive in 2000. It aims to improve the ecological quality of rivers and lakes in the EU.