Planiceps-
Took this pic at the SHEDD aquarium in chicagoland. Very beautiful fish to see in person. Didn't seem to be very active, but i suppose that might change at feeding time. Supposedly these guys get really long and not as broad as similar pimelids.
Here are the known species of The Genus Sorubim: Sorubim cuspicaudus(36"), Sorubim elongatus(14"), Sorubim lima(22"), Sorubim maniradii(10"), and Sorubim trigonocephalus(22").
I think i may be wrong about the planiceps, i just realized it doesn't have as large of pectoral fins as is usual of the species...does looks like some sort of "sorubim" though probably a sort of sorubichmys. Sorry, just rambling on, lol