Pink Flying Fish pop up in groups and fly around the place, trying to hit Luigi. This causes five HP of damage to be lost for each hit. Like mice, they have no HP (as opposed to zero HP like Ceiling Surprise or Purple Bomber) and can be sucked up easily by the Poltergust 3000. The Flying Fish found in the Pipe Room are identical, except they are green and considerably faster than those found in the Courtyard. In the PAL version of the Hidden Mansion, the green variants replace the pink ones in the courtyard.
Possibly a play on「とっと」(totto, a childish word meaning "fishie") and「プー」(pū, onomatopoeic term meaning "poof"), likely related to the noise they make upon spawning