That's actually not a niger. It's a decrepit old raphael catfish, platydoras armulatus. His stripes have gone gray so they are hard to see. And he was thin when I found him, so he looks a bit off. Now he's fat, happy, and the first out of the cave (out of seven catfish!) when lights go off!
And the fools had him in the Koi/plant display tank at about 72º I think. A bit cool for a tropical cat, don't you think? They let me have him for free when I said "125 gallon tank".