it is a synodontis
maybe Synodontis Eupterus which is commonly called the feather fin
this is the cat that i bought at petco that they sold and still sell as a cory
mine got to be 5 in
but it could be one of the other variations... they all look soo similar!
i would go with Synodontis eupterus. individuals vary in exact appearance (i dont think i have ever seen one like the one in the pic from that liveaquaria link). that is definitely what i thought when i saw the pic, eupterus.