Hey, is a baby catfish called a kittenfish?
Oh, and sorry about my voice. It's scratchy due to allergies, it's always rather nasal. I apologize, but can't help that. And, what I was going to say but was cut off, is, Zoidberg is manic. He'll just go nuts and starts racing around the tank, up and down. The other fish ignore him. Guess they don't recognize him as a native species and thinks if they ignore him he'll go away.
Maybe it's a 'cat' thing. Cats (felines) go crazy like that, too, for no apparent reason sometimes.