This line always perplexed me as a kid.
I got (still get) stuck on the overlap between moving, and steering. Moving like a fish seems to include sinuous paths, schooling with sudden acceleration and darts to the side, etc... nimbleness and speed.
I understood it was a proxy for "accelerates like/is as fast as" but found that unsatisfying.
Also, cow works to evoke large, stubborn perhaps, unresponsive... but was an odd choice in as much as few try to steer cows. Shepherd, maybe. A water buffalo or ox or even mule felt like a missed opportunity, since they are prototypically steered and there is a sense of their owners/drivers laboring against their desire to not labor...
Total Nicolson Baker rabbit hole, just a specific reading experience that has always stood out from that series. I have uttered that line countless times over the years in various contexts, including while dancing late at night on the playa.