Not so much a committed fisherman in Krull as a committed home-and-wife avoider, who was distracted by Death turning up to try out his new fishing fly. In regards to the latter's less-than-earthly disposition, this was a prehistoric mosquito that became extinct when its primary source of food, the woolly mammoth, perished thousands of years ago.
In the tsunami of piscine life struggling to get out of the way of the ensuing slaughter, Mims lost his footing and, in every sense of the word, underwent a near-Death experience.
While Mims was vaguely grateful that the tall dark mysterious stranger had saved him from drowning (although the downside was that he then had to return to Gwladys, who then moaned about his trailing dirty water into the house, and look at the state of your clothes, Terpsic Mims), the one thing that will haunt him till his dying day is that the tall dark mysterious stranger explained his actions by saying FOR LATER. What could he have meant by that...
The name Terpsic may have been inspired by Terpsichore, the Greek muse of music and dancing.