Arius is a genus of catfishes (order Siluriformes) of the family Ariidae. The genus Arius is distributed in brackish and fresh waters of Eastern Africa and south to Southeast Asia.[1]
Defining the limits so that Arius can form a natural grouping has always been a problem. The genus was never properly defined, and many species previously classified in Arius are now in other genera. Recent authors have recognized this genus as nonmonophyetic, rejecting that the genus is a natural grouping. Two unnamed groups are distinguished by accessory tooth plates, which are either very elongated and bearing molar-like teeth, or are oval shaped or subtriangular and bearing acicular (needle-like) or conic teeth.[1] A. jatius lacks these tooth plates, but has been included in this genus based on its adipose fin and lateral line.[1] The recognition of Arenarius as a junior synonym of Arius is tentative and needs to be further investigated.[1]
Arius species have three pairs of barbels, including the fleshy and cylindrical maxillary barbels and two pairs of mental barbels. The base of the adipose fin is moderately long, about half the length of the base of the anal fin.[1]
Currently, 23 living species are recognized for this genus.
In addition, a fairly extensive fossil record exists, encompassing several species, but mainly represented by otoliths.