Topic summary
Arno River

Extracted from the Wikipedia article Arno.
Ecology
The Arno river has been strongly affected by non-native species: over 90% of fish species and 70% of macroinvertebrate species in the area around Florence are alien species. These include the European catfish, channel catfish, Crucian carp, common bleak, topmouth gudgeon, New Zealand mud snail, and killer shrimp. The mud crab has been found in the river near Pisa.