Abstract: This research was carried out at 35 stations in 16 different streams on the Biga Peninsula during the spring and summer of 2000 and 2001 to determine the freshwater ichthyofauna and community features. In addition, some physical and chemical parameters of the streams were determined in their natural environment. Fourteen taxa belonging to 5 families were determined. Leuciscus cephalus, Petroleuciscus borysthenicus, Rhodeus amarus, Phoxinus phoxinus, Chalcalburnus chalcoides, Barbus tauricus escherichi, Gobio gobio, Capoeta capoeta bergamae, Vimba vimba, Cobitis fahirae and Neogobius fluviatilis are recorded for the first time from the Biga Peninsula. The most abundant species in the study area was L. cephalus. Fish communities in the streams were analysed, where 3 different groups were formed at a level of 50% similarity. Larger streams are determined to be the richest habitats in terms of species diversity.