"Picuda" got underway from Pearl Harbor for her first war patrol on 17 February, setting course for waters off the Caroline Islands, and entering her designated patrol area on 29 February. In an area not far from Truk, she sank 2672-ton ex-gunboat "Shinyo Maru" on 2 March, going deep to evade a string of 15 depth charges dropped by searching corvettes. On 18 March, "Picuda" changed course to patrol along the Saipan-Palau shipping lanes. She scored hits on a large enemy tanker that afternoon but was held down by two destroyers while the target escaped. She was off Yap Island a few minutes after midnight of 19 March, and sent 1504-ton freighter "Hoko Maru" to the bottom with two torpedo hits.