This rare kanji has no clear standalone meaning. Treat its meaning as uncertain.
瘹 combines the sickness radical 疒 with 釣, but the historical development and original meaning are uncertain.
The sickness enclosure 疒 wraps around 釣 (fishing), but the overall meaning is unclear. Picture a rare illness that makes someone obsessively fish, though this is just a mnemonic.
For チョウ, imagine a long-serving chief named Chou who catches a strange sickness while fishing: Chou -> チョウ, and the sickness enclosure 疒 contains 釣 (fishing).