Hemiancistrus species differ from other members of the Panaque clade lacking the synapomorphies of the other genera and having the dentaries meeting at an angle greater than 120°; in Peckoltia species, the dentaries meet at less than 90°[3] Generally, Peckoltia are considered to be those that have dorsal saddles and bands in the fins, while Heminancistrus have spots and uniform coloration.

The remainder of the taxa that do not have established genera that they can be placed in will be recognized as species groups in Hemiancistrus in single quotes until they can be examined further.

[3] The genus exhibits a large distribution area ranging from the Panama, in Central America, to southern Brazil.

[6] Many Hemiancistrus originate from the Guyanas, the Negro and Orinoco and the southern Amazonian tributaries.

[2] These fish prefer flowing water habitats of medium to large rivers.

Like many other catfish, Hemiancistrus have strong pectoral and dorsal fin spines that can be locked outwards as a defense.

guahiborum is only rarely imported; despite being common in its natural habitat, it is less attractive than 'H.'