Was Pierre Aronnax was a captain?

No, Pierre Aronnax was not a captain. He is a fictional character from Jules Verne's novel "Twenty Thousand Leagues Under the Sea." Aronnax is portrayed as a French marine biologist and professor at the Paris Museum of Natural History. In the novel, he joins an expedition aboard the USS Abraham Lincoln to hunt down a mysterious sea monster that has been terrorizing ships. However, after encountering the creature, which turns out to be the submarine Nautilus commanded by Captain Nemo, Aronnax, along with his companions Conseil and Ned Land, becomes a prisoner aboard the submarine. Throughout the story, Aronnax serves as the narrator and main protagonist, chronicling their adventures aboard the Nautilus.