Paedocypris carbunculus Britz & Kottelat 2008

Distinguished from other members of the genus Paedocypris by the shape of the head blotches. Can be differentiated further from Paedocypris micromegethes by the possession of the following characters: middorsal stripe with chromatophores in three rows (vs. in a single row); head kidney pigment (vs. absence); well developed opercular, subopercular, preopercular and branchiostegal rows, and isthmus gular pigmentation (vs. absence or consisting of only a few chromatophores); chest spots (vs. absence); chest blotch well developed (vs. poorly developed or absent); and preanal larval fin fold in adult females (vs. absence). Can be separated further from Paedocypris progenetica by the presence of median row of the middorsal stripe formed by separated individual chromatophores (vs. chromatophores forming an uninterrupted line) and sparse pigmentation on the upper and lower lips (vs. heavy pigmented lips appearing uniformly black) (Ref. 78740).

Occurs in areas with slow current, usually forming small shoals approximately up to 100-200 individuals, most abundant near or under overhanging structures or submerged vegetation. The type specimen was collected in a small stream, 3-6 m wide and 0.5 to 2 m depth, with substrate ranging from sand to detritus and peat, with flowing blackwater (Ref. 78740).

Paedocypris carbunculus is a tiny species of cyprinid fish endemic to peat swamps and blackwater streams in Central Kalimantan, Borneo, Indonesia. It is the most recently described species of the three in the genus Paedocypris and it reaches up to 11.5 mm (0.45 in) in standard length. This shoaling species has been kept and bred for several generations in aquariums.

The male Paedocypris carbunculus has a unique pelvic fin, along with a keratinized pad, that allows the male to latch on to the female for sexual reproduction.