Acrochordonichthys rugosus (Bleeker 1847)
Identification: Acrochordonichthys rugosus has a moderately compressed body, a wide head (20-29% SL), a convex snout when viewed dorsally, a comparatively deep caudal peduncle (5-7% SL), long nasal barbels (7-16% head length), and an angular posterior margin on the adipose fin. The head is covered with small, indistinct tubercles. Tubercles on the body are arranged in 5-6 horizontal rows on each side. The dorsal surface of the head is chestnut brown. Small dark brown patches are sometimes randomly scattered on the dorsal surface of the head. The lateral and sometimes ventral surfaces of the body posterior to the dorsal-fin base are dark brown. There is a chestnut brown saddle on the dorsolateral surface over the adipose fin, which may be absent in some specimens and replaced by a longitudinal series of chestnut brown spots merging to form patches. The belly, chest and ventral surface are lighter in color and lack spots. The dorsal, pectoral, pelvic and anal fins are cream-colored with 1-2 dark brown bands; one band usually occurs at the base of the fins and the other near the edge. Some specimens have a reversed color pattern on the fins resulting in dark brown fins with cream-colored bands. The cream-colored caudal fin has a dark brown band near the edge and a dark brown patch at the base of the caudal peduncle. The cream-colored or dark yellow barbels and pectoral spines sometimes have dark brown spots on the dorsal surfaces. Some specimens have dark brown coloring throughout, lacking spots and a saddle. The premaxillary toothband is not exposed when the mouth is closed. The stout pectoral spine has 1-7 serrations on the posterior edge. There are 5-7 branchiostegal rays and 35-37 vertebrae.
Range: This species is found in the Solo, Ciliwung and Citarum drainges in Java, the Barito, Kapuas, Mahakam and Rajang River drainages in Borneo, the Bernam, Terengganu, Mae Nam Sungai Kolok, and Pattani drainages in Peninsular Malaysia and southern Thailand, and the Musi and Tulangbawan River drainages in Sumatra.
Habitat: A. rugosus is found among woody debris in current in creeks and small to medium-sized rivers.
Similar species: A. chamaeleon has shorter nasal barbels, a head with a more gently sloping lateral margin and a broadly rounded snout. A. falcifer has an adipose fin with a more rounded posterior margin. A. pachyderma has a uniformly cream-colored body, and the posterior edge of the pectoral spine lacks serrations.
Information from Ng, H. H. and P. K. L. Ng. 2001. A revision of the akysid catfish genus Acrochordonichthys Bleeker. Journal of Fish Biology 58: 386-418.