Platytropius siamensis was a species of schilbid catfish (order Siluriformes) family Schilbeidae.

[2] It originated from the Chao Phraya and Bang Pakong Rivers in Thailand.

[1][2] It inhabited lower to middle reaches, mainstreams, tributaries, and larger marshlands.

[3] The species has been declared extinct in 2011 by the IUCN Red List of Threatened Species, because despite periodic surveys it has not been encountered since 1975–1977.

[1] P. siamensis was carnivorous, feeding on insects and shrimps.