Hey V.J. (thebiggerthebetter), don't recall commenting on the i.d. of your former cephalosilirus but from the photo's shown it looks like either two c. apurensis or the dark one could be c. nigricaudus, that is if it came from Suriname, of course. C. fowleri from Brazil are easy to i.d based on their flatter profile and lack of belly markings compared to c. apurensis but c. nigricaudus (latin for black tail) closely resemble apurensis, just usually darker. Can't generally go by color/markings in these fish as they can change regularly according to individuals plus mood and environmental lighting are factors as well. Gluttons they are, the first day home, my baby apurensis ate 20 live goldfish! Still looking for a c. nigricaudus or the fourth species from Guyana...