My possum ("Patty"
) eats anything. Cookies, veggies, salmon, frogs, grass, veggies, fruit, slugs (YEA!) or dead animals. Once I had a dead fish that I tossed out onto the lawn and she was there within 30 seconds to eat that sucker. They are not hunters and will not actively seek your fish, but they do like fish. They are more scavenger- eating the stuff that just turns up.
My Patty has been living under my deck for years.
I finally figured out that the growling under my deck was a conflict between the possum and the groundhog. I hope they got that all figured out, cuz they're still there.
I don't think they're ugly, I think they're adorable!