Bare-chested and handcuffed, the men were paraded in front of local and international media as the Nigerian naval officers described how they stormed the ship on Saturday and arrested the pirates off the coast of Sao Tome and Principe, West Africa.
Officers engaged in a gun battle with the pirates on board, killing one of them, the Nigerian navy said. His body was later seen being carried from the ship on Monday at the Lagos naval base.
The Saudi Arabian tanker, Maximus, was taken on February 11 with at least 18 crew, including 10 Indian sailors.
Two of the crew are still missing after they were taken hostage by two pirates who escaped in another vessel. The hostages are believed to be from India and Pakistan.
The suspected hijackers, all Nigerians, were named as Captain Mike Ugborama, Ayo Joshua, Marcus Adesoji, Adeyemi Paul, Oluwafemi Samuel, and Collins Friday.
Among the haul recovered from the ship were AK47s, magazines, bullets, different currencies, satellite phones and even protection charms from local traditional medicine men.
Rear Admiral Henry Babalola told CNN the ship, chartered by a South Korean company, was carrying 4.700 metric tons of diesel, which the pirates hoped to sell on the black market. They had also renamed the vessel MT-ELVIS-5 to try to avoid detection.
The Indian defense attache, Capt. Gautam Marwaha, was at the scene to welcome the rescued crew. He told CNN no ransom demand had been received yet for the missing crew members.
However he hailed the operation a "success," adding "as we say in the Navy: 'Bravo, Zulu to the Nigerians.'"