Mastacembelus pentophthalmos Gronow, 1854 Macrognathus semiocellatus is a species of ray-finned fish endemic to Cambodia, Laos and Vietnam; it found in marshlands and vegetated water bodies in Mekong Chao Phraya River and Mae Klong.

[2] It spends its time during the day buried in silt, sand or fine gravel and forages at night for benthic insect larvae, crustaceans and worms.

[3] It is listed as Least Concern as it is locally and seasonally common and its threats are not significant and there is no need for conservation protection; the threats are pollution and wetland removal.

It is seen aquariums and is also fished and exported from Cambodia to Thailand and other countries.

This Synbranchiformes-related article is a stub.