Helogenes castaneus (Dahl, 1960)
Identification: Helogenes castaneus is readily distinguished from H. uruyensis in the number of anal-fin rays (43-49, vs. 32-37) and a number of morphometric differences. The presence of eight principal rays in the lower lobe of the caudal fin in H. castaneus separates it from H. marmoratus, which has nine principal rays in the lower lobe of that fin. The 43-49 anal-fin rays of H. castaneusdiscriminate that species form H. gouldingi, which as 39-43 anal-fin rays. Those two species are also separable in various morphometic characters, most notably their relative snout lengths and in the distance between the rayed and adipose dorsal fins. Maximum size: 47 mm SL.
Range: Helogenes castaneus is known from the upper Orinoco, Guaviare and Meta River basins, Colombia.
Information from Vari, R. P. & H. Ortega. 1986. The catfishes of the Neotropical family Helogenidae (Ostariophysi: Siluroidei). Smithsonian Contributions to Zoology, 442: 1-20.