Monostichodus is a genus of small characins native to Central African river systems, recorded in the atlas from the Democratic Republic of the Congo and Gabon. Atlas species run about 2–3.5 in, similar in size to many small forest-stream characins found alongside them in Congo basin tributaries. Published biology on the genus is thin, and there is not enough sourced detail here to describe its habits with confidence beyond general characiform traits - a slim, laterally compressed body built for life in moving water.
The genus sits well outside the mainstream aquarium trade - none of its three atlas species (M. elongatus, M. lootensi, M. mesmaekersi) is established in the hobby, and detailed husbandry information has not been published. All three are currently assessed as Least Concern, consistent with a genus that occupies a reasonably wide swath of Central African river habitat rather than a single threatened watershed.