Arnissa (Greek: Άρνισσα; Bulgarian: Острово, Ostrovo, before 1926: Όστροβον - Ostrovon) is a town in the Pella regional unit of Macedonia, Greece. It is located near the Lake Vegoritida and Mount Kaimakchalan and is the seat of the Vegoritida Municipality. It has a population of 1,550 (as of 2001).
The Battle of Ostrovo was fought near the town in 1041. In 1845 the Russian Slav scholar notes Ostrovo as a nice village situated near a lake and populated by Bulgarians and Turks.
- Todor Hristov Simovski, The Inhabited Places of the Aegean Macedonia (Skopje 1998), ISBN 9989-9819-4-9, p. 54
Coordinates: 40°48′N 21°50′E / 40.800°N 21.833°E