Okay, so Topo gets all the press were Aquaman's exploits are concerned. After all, he was a named in over sixty adventures. However, he was not the first finny friend with four pairs of arms... that honor goes to the unappreciated Octy.
Yes, Octy, an original name for an octopus, isn't it? While Topo of Earth-One and Octy of Earth-Two appeared in different shades of grayish black, they were each faithful companions of the Sea King.
And gifted as well, displaying near human level of intelligence including the ability to play instruments and proficient in archery. Truly among Aquaman's most valued of allies, even counting fellow superheroes he'd encounter later.