for Majuro at the close of her patrol, on April Fool's Day 1944, the submarine torpedoed and sank the freighter Minami Maru (2398 tons – formally the Norwegian Solviken). at Kitadaitōjima. Flying Fish closed out her patrol and arrived at Majuro 11 April 1944. Clearing Majuro harbor 4 May, Flying Fish sailed for her tenth war patrol, coordinated with the assault on the Marianas scheduled to open the next month. First she covered shipping lanes between Ulithi, Yap, and Palau, coming under severe attack after one of her torpedoes exploded just outside the tubes on the night of 24 – 25 May when she was detected while attacking a four-ship convoy. At dawn, however, she had got back into position to sink the Japanese troop transport Taito Maru (4466 tons) loaded with 5,300 aviation gasoline cans, 2,500m3 of arms and 500-tons of cement, and the passenger/cargo ship Osaka Maru (3740 tons). The Osaka Maru was also out of Saipan bound for Palau in the same convoy, carrying 824 passengers and materials for the war effort. 97 passengers and all of the cargo went down with the ship. Along with other American submarines, she then headed to take up a patrol station between the Palaus and San Bernardino Strait, from which she could scout any movement by the enemy fleet out of its base at Tawi in the Sulus while the Marines were landed on Saipan. On 15 June, the day of the invasion, Flying Fish spotted a Japanese carrier force emerging from San Bernardino Strait bound eastward. Her prompt report of this movement enabled a sister submarine, , to sink the carrier Shōkaku four days later while American carrier aircraft broke the back of Japanese naval aviation in the Battle of the Philippine Sea. Flying Fish remained on her scouting station until 23 June, then sailed for Manus and Brisbane, arriving there 5 July. Eleventh war patrol, October – November 1944 On 1 August 1944, Flying Fish was escorted out to sea from Brisbane, Australia, to begin her eleventh war patrol, this one taking her to Davao Gulf, the coast of Celebes, and along the shipping lanes from the Philippines to Halmahera. She departed Brisbane in the company with the submarine , which was to share a patrol area with her. On 8 August, Flying Fish and Flounder arrived in the Admiralty Islands and moored alongside the submarine tender to