During the early morning hours of 30 January 1945, Blackfish made an approach on two large sampan-type vessels. At 02:18, she launched two torpedoes, both of which appeared to hit, but no explosions resulted. Blackfish′s crew manned her guns, and at 04:35 trained all of them on the nearest sampan. Although the guns again failed to fire, the 20-millimeter gun and .50-caliber machine guns riddled the sampan, causing its sails to collapse and its masts to fall. Blackfish left the sampan in a sinking condition with its decks awash, then shifted her attention to the second sampan, which opened all her sails in the hope of escaping. Blackfish closed to and opened fire while circling the sampan, which in desperation attempted to ram Blackfish. After 10 minutes of firing the 50-caliber machine guns overheated and the 20-millimeter gun jammed, so Blackfish retired from the battle to work on her guns. On 1 February 1945 Blackfish again engaged a group of similar ships. The skirmish began just after moonrise when she approached several sampans and trawlers traveling in pairs. In the ensuing firefight, she sank at least three ships and damaged eight others with , and 50-caliber fire. The sampans retaliated with small arms fire, which had little to no effect on Blackfish. During the firefight, Blackfish′s radar picked up three large surface vessels approaching, so she quickly vacated the area. On 2 February 1945, Blackfish reported the previous day’s action, then received orders to join another wolfpack also consisting of the submarines and . As of 3 February she was headed for the Luzon Strait. On 4 February, she received word that the sampan she attacked might have been Chinese, to which Sellars responded that he "considered that possibility each time before shooting but with return fire, attempts to ram, regular patrol in pairs, and non-junk-like hulls, the enemy indications overruled." Blackfish spent the remainder of her time on station patrolling and conducting lifeguard duties. She departed her patrol area in company with Batfish on 17 February 1945 and shaped a course for Apra Harbor on Guam. She arrived there on 21 February 1945 and moored to the port side of the submarine tender , ending her patrol. She received credit for sinking the sampans she engaged by gunfire, but the Submarine Combat Patrol Insignia was not granted for the patrol. The ship′s final report also congratulated Sellars on his