Inventory of fishes in the upper Pelus River (Perak river basin, Perak, Malaysia) Author Ikhwanuddin, Mat Esa Mohd Author Amal, Mohammad Noor Azmai Author Aziz, Azizul Author Sepet, Johari Author Talib, Abdullah Author Ismail, Muhammad Faiz Author Hashim, Nor Rasidah text Check List 2017 2017-08-18 13 4 315 325 http://dx.doi.org/10.15560/13.4.315 journal article 10.15560/13.4.315 1809-127X Mystus cavasius ( Hamilton, 1822 ) Mystus cavasius Hamilton 1822: 39 . Mystus mukherjii Ganguly and Datta 1975: 439 . Material examined. Table 1 ; Figure 4d . Species of Mystus are small to medium-sized bagrid catfishes occurring in South Asia. This species was iden- tified by having 1 dorsal-fin spine; 7 dorsal-soft rays; no anal-spine and 10–11 anal-soft rays. The species is distinguished from its congeners by having the maxillary barbels extended beyond posteriorly the caudal-fin base in adults, but in young specimen not extended beyond the anal fin. Color is grayish, with a somewhat well-defined mid-lateral longitudinal stripe; dark spot emphasized by a white or pale area along its ventral margin located just anterior to the first dorsal spine. It can be found in tidal rivers and lakes and also in canals, ditches, ponds, and inundated fields ( Talwar and Jhingran 1991 ).