Cetopsidium minutum (Eigenmann, 1912)
Identification: Cetopsidium minutum differs from all other species of Cetopsidium in the length of the pelvic fin (tip of fin reaching posteriorly to the anal-fin origin versus only reaching or falling short of the vent, respectively). Cetopsidium minutum differs from all other species of Cetopsidium with the exception of C. pemon in the length of the pectoral fin (tip of fin reaching to the vertical through the pelvic-fin insertion versus falling distinctly short of that line, respectively). Cetopsidium minutum further differs from C. orientale and C. roae in the relative alignment of the dorsal and ventral profiles of the portion of the body posterior of the terminus of the base of the dorsal fin (converging posteriorly versus running in parallel, respectively). Cetopsidium minutum also differs from C. roae in the relative position of the vent (located proximate to the base of the anterior most anal-fin ray versus located distinctly anterior to the base of the anterior most anal-fin ray, respectively). Maximum size: 21 mm SL.
Range: Cetopsidium minutum occurs in the Potaro River and middle portion of the Essequibo River of Guyana.
Information from Vari, R. P., C. J. Ferraris Jr. & M. C. C. de Pinna. 2005. The Neotropical whale catfishes (Siluriformes: Cetopsidae: Cetopsinae), a revisionary study. Neotropical Ichthyology 3:127-238.