[Niedowidek]

As for acoustic torpedoes, there's an example of type IX U-505, which - while being captured - carried three of them:

"The U-boat was tied up at the Navy Yard in Bermuda and the remaining contents of the boat inspected in detail. Fourteen torpedoes, together with their detonating pistols and any other related parts, were inventoried from the boat. Two were T-5 accoustic homing torpedoes (a third had been fired from the #5 tube in the stern) and five were air powered. The torpedoes were sent to Washington on several ships to ensure at least one of the shipments arrived safely. Tests were conducted on the T-5s to discover the frequency upon which they operated. This helped ASW technicians in their quest to make existing foxing gear more effective as a decoy against them."

Savas, Theodore (2004-06-19). HUNT AND KILL: U-505 and the Battle of the Atlantic (p. 164). Casemate Publishers. Kindle Edition.

Bear in mind that full loadout of torpedoes for type IXC when leaving port should be 22, but I'm pretty sure that U-505 didn't launch more homing torpedoes during its last patrol than mentioned above.