Understandably angered, Arthur tracked down Black Manta to kill him, but upon reaching the boat where the mercenary was hiding out, Arthur accidentally killed Black Manta’s father instead.
While Black Manta has been Aquaman’s arch-nemesis for 50 years, the villain’s father only became relatively important during Geoff John’s New 52 Aquaman run.
Since Black Manta’s surname has never been revealed in the comics, it’s plausible that Jesse Kane could be his father, and if Kane dies in the movie, perhaps this “fateful interaction” will be the event that leads Black Manta and Aquaman become adversaries in the DC Extended Universe.
That’s why Black Manta hates Aquaman so much in the current DC continuity.