According to this dichotomous key, any catfish must have
a double dorsal fin, a small fin on the back near the tail, and barbs near the mouth.
a single dorsal fin, no small fin on the back near the tail, and barbs near the mouth.
a double dorsal fin, a small fin on the back near the tail, and no barbs near the mouth.
a single dorsal fin, a small fin on the back near the tail, and barbs near the mouth.