louse

milkfish (Chanos chanos)

(lit.) when covered with lice, one doesn't feel the itching anymore (idiom); (fig.) to be past worrying (about sth)

(lit.) when covered with lice, one doesn't feel the itching anymore, and when up to one's ears in debt, one ceases to worry about it (saying); (fig.) to be past worrying (about sth)