There may not be, but (even if I did like to eat fish) I would NEVER eat a fish out of our city park's pond and it's full of bluegill. That water looks bad because it IS even if there might not be ammonia. There are very few places with "pristine" water anymore. Of course ammonia isn't good for any fish
BTW, would you happen to know where your friend got a shirt that looks like your avatar? I want one