Piranha was laid down 21 June 1943 by Portsmouth Navy Yard in Kittery, Maine; launched 27 October 1943; sponsored by Mrs. William S. Farber; and commissioned 5 February 1944.

When Peleliu, deemed essential for the liberation of the Philippines, had been seized, Piranha’s group dissolved and she searched for targets westward along the 20th parallel, engaging an enemy patrol craft 9 October.

During her third war patrol, again with an attack group, besides seeking worthwhile targets in the East China Sea 19 November to 13 January 1945, Piranha served as lifeguard during B-29 strikes on Kyūshū.

Piranha was foiled by a large fleet of fishing junks from making a rapid approach on a convoy reported leaving Hong Kong 5 March.

[7] On 11 March, a U.S. Navy PBM Mariner flying boat attacked her, dropping four bombs as she took evasive action and headed for deeper water on the surface.

[7] On 20 March, an Allied aircraft which Piranha′s crew thought was most likely a United States Army Air Forces B-24 Liberator bomber bombed Piranha as she maneuvered evasively and submerged.

Hair-raising encounters with submarine chasers and aircraft were rendered infinitely more dangerous by being fought so close offshore, where she had little water depth for maneuver.