This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
鱫 combines 魚 (fish) with 愛, which likely contributes the sound アイ. The exact historical development is uncertain.
The kanji has 魚 (fish) on the left and 愛 (love) on the right. Imagine a fish you love so much that you give it a special name, but its exact meaning remains a mystery.
For アイ, picture yourself saying 'I' love this fish: 'I' -> アイ, and your affection for the fish helps you remember the reading.