Fish: The hairless puppy

Quote of the Day. About fish introductions in Europe (from: Holtik, J. 1991. Fish introductions in Europe with particular reference to its central and eastern parts. Can. J. Fish. Aquat. Sci. 48 (Suppl. 1): 13-23):

"The first was the brook trout, introduced to the United Kingdom in 1869, followed by the chinook salmon...two easily confused American catfishes, the black bullhead (Ictalurus melas) and the brown bullhead (I. nebulosus), and six centrarchids..."

My initial reactions, in order of occurrence, to above quote:

1. Aw! "easily confused" is the most adorable fish character trait ever!
2. How do they know they're easily confused? Do the fish swim in circles a lot and bump into things? Do they wrinkle their fishy brows?
3. How would you test that in a lab setting? I'll bet they're easy to catch, though
4. Oh, wait....I get it

I still maintain that my initial interpretation of the text, while completely wrong, is far more interesting.