fresh, new, delicious, rare, few
鱻 centers on the idea of freshness and newness, like a just-caught fish. The sense of deliciousness comes from that peak freshness, while the rare/few sense likely extends from the idea of something being so fresh it is uncommon.
鱻 is a triplication of 魚 (fish), likely emphasizing abundance or extreme freshness. The exact historical development is uncertain, but the visual repetition of fish is a clear semantic intensifier.
Three fish 魚 stacked together: one fresh, one new, one delicious. With three fish, freshness is tripled, making it rare and few can enjoy such a catch.
For セン, imagine a fresh fish being sold for just one cent: cent -> セン, and the triple-fish kanji emphasizes how incredibly fresh it is.