Fiske began her service as a convoy escort with a voyage from Norfolk to Coco Solo, Panama Canal Zone to New York between 12 and 25 November 1943. On 3 December, the escort ship cleared Norfolk on the first of three convoy assignments from Norfolk and New York to Casablanca. During the third of these, on 20 April 1944, her convoy came under attack by German torpedo bombers in the western Mediterranean, but none of the enemy planes came within range of Fiske.
Completing her Casablanca runs with her return to New York 21 May 1944, Fiske joined the hunter-killer group formed around Wake Island (CVE 65) at Norfolk 10 June. Five days later, her group sailed to patrol across the Atlantic, putting into Casablanca to replenish 20 to 24 July.
On 2 August, during a special hunt for submarines known to be transmitting weather information from stations in the central Atlantic, Fiske and Douglas L. Howard (DE 138) were detached from the task group to investigate a visual contact both had made. The contact, surfaced U-804, quickly dived, but the two escorts picked it up on sonar and began their attack approach.
Without warning, Fiske was torpedoed on her starboard side amidships. Within 10 minutes, she broke in two and had to be abandoned. Thirty of her men were killed and 50 badly wounded by the explosion. Survivors were rescued by Farquhar (DE 139).
Fiske received one battle star for World War II service.