There are numerous examples of visual attraction in animals. An absolute classic of an experiment, taught to most/all evolutionary biology students, is the widowbird tail length experiment by Andersson. He experimentally manipulated the tail lengths of male widowbirds at random. Some tails were made longer and some shorter. From this experiment Andersson showed that females choose males with longer tails more preferentially. Another classic example is the lek mating system where there is a bias in reproductive success towards attractive males, in some cases 10-20% of the males get 70-80% of the matings.
A lek is an aggregation of males that gather to engage in competitive
displays that may entice visiting females who are surveying
prospective partners for copulation. Leks are commonly formed
before or during the breeding season. A lekking species is defined by
the following characteristics: male displays, strong female mate
choice, and the conferring of male indirect benefits. Although
lekking is most prevalent among avian species, lekking behavior is
found in a variety of animals such as insects, amphibians, and
Beauty could be a an example of a an indicator trait:
Indicator traits are those that signal good overall quality of the
individual. Traits that are perceived as attractive must reliably
indicate broad genetic quality in order for selection to favor them
and for preference to evolve.
I'm sure there are some studies in fish, likely guppies or zebra fish, which gave individual fish the opportunity to visually assess potential mates (placing tanks next to each other and observing courtship) which would be very similar to your hypothetical duck example. Despite often being a paradox, female mate choice is well documented. Further, male mate choice is now coming to light, even in species where female mate choice and male-male competition exists.
I don't think selection on "beauty" would require some kind of particularly special neural system, obviously some visual capacity is necessary for visual attraction and some basic neural pathways linked to that. I have done experiments myself in Drosophila simulans which looked at good gene benefits of mating with attractive males (indirect genetic benefits of female mate choice) and another which assessed precopulatory selection (female mate choice) for a secondary sexual character in the same species. Even in such a small-brained species there appears to be some degree of (partially visual) mate choice going on.