From translingualTilapia, from Tswanatlhapi(“fish”).
The drag race slang usage is a reference to the comment by Gia Gunn on entering Ru Paul's Drag Race (season 6) "Just landed like fresh tilapia".
Well I dined last night with Scarface Ron On tilapia fishcakes and fried black swan.
(dragslang) A fishy(resembling a cisgender woman)drag queen; a drag queen who could pass for a woman, as opposed to one who is exaggeratedly feminine.
2019 June 13, Sam Damshenas, “Drag Race star Plastique Tiara wants to be a "pioneer" for the queer Asian community”, in Gay Times, London: Gay Times Ltd, →ISSN, →OCLC, archived from the original on 2021-08-01:
Vietnamese tilapia Plastique Tiara was at the forefront of one of Drag Race's most controversial eliminations earlier this year. Although the Texan performer and biological woman was leaving us gooped week-after-week with her runways, she was – spoiler alert! – eliminated in eighth place after lip-syncing against Miss Vanjie, despite having a better track record.