Refer to this portion of a dichotomous key for fish identification to answer the question. 1. (a) Has a single dorsal fin ® 5 (b) Has a double dorsal fin ® 2 5. (a) Has small fin on back near tail ® 6 (b) Has no fin on back near tail ® 7 6. (a) Has barbs near the mouth ® Catfish (b) Does not have barbs near the mouth ® 10 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.