I think they might be too young to tell the species, though of course hard to tell from that pic but they still look small. Dug out a species guide from Dr. Wayne Leibel from his article on them way back in the December 1995 AFM issue ...
Hope this helps!
It looks like the caudal fin is spotted in the pics, but hard to tell. Would need a better straight on side view to tell more, though honestly I haven't found the guide useful at the LFS cause I never bring the magazine with me. :lol: Though it doesn't look like their band is continuous, so am guessing M. festivus given the spotting I see in the fins, the band, and the short nose but just a guess!1a. Reticulated back:Mesonauta insignis - single wide dark vertical bar above the abdomen (not two), dark continuous lateral band, unpaired fins spotted, most slender, long nosed species. Distribution: upper Rio *****, Rio Orinoco
1b. Non-Reticulated back:
2a: Discontinuous lateral (oblique) band:
M. festivus - upaired fins indistinctly spotted, most deep bodied, short nosed species. Distribution: Paraguay and Bolivian Amazon basins, Rio Jamari and lower Rio Tapajos
M. acora - distinctive mottled color pattern lateral band runs only 1/3 of the way to the dorsal fin, then fades out. Distribution: Tocantins and Xingu drainages
M. egregius - back brownish, but with no reticulation, lateral band is a row of dark blotches, unpaired fins unspotted. Distributions: Colombian Orinoco basin
2b: Continuous dark lateral (oblique) band: M. mirificus - lateral band fades slightly towards dorsal, back not reticulated, dorsal fin indistinctly spotted, caudal and anal fins unspotted. Distribution: Peruvian Amazon
Hope this helps!