This is a really good question that I can't come up with a good answer for. I would say that my overall favorite fish is the Round Goby. I love these guys so much, they have so much personality and have pretty much become a part of the ecosystem in the Great Lakes and it's tributaries. They have unique looking faces, and their origins have always made them interesting for the main reason that I had never seen any fish native to Eastern Europe (or any of Europe for the most part). I guess the only thing I don't like about them is maybe the downsides they have had for the environment, and maybe the fact that I've just kind of spent so much time around them for so long that they aren't as special as they used to be for me. Of course, there are a lot of other fish I am very fond of, such as things like Mottled Sculpin, Rainbow Darters, and Riffle Dace. But I think for an overall answer, the Round Goby is my favorite.