Duckling feeding fish? Nope.
Remarkable duck behaviour always has my full attention. When a video, taken in Japan, titled ‘baby duck feed the carp’ was posted on YouTube, I studied it carefully. That’s because there is no previous report of any duck engaged in feeding fish (in contrast to reports of? ducks feeding on fish — although that is doubted sometimes).
The duckling featuring in the short video is a so-called spotbill Anas poecilorhyncha (probably of the East-Asian subspecies zonorhyncha). My interpretation of the video differs from the general consensus. The duckling is eating some kind of dry food, maybe even specially prepared food for carps, placed on a small tray just above the surface of a pond, maybe even the site where the carps are usually fed. The duckling and its feeding table is surrounded by a dozen carps Cyprinus carpio, of the ornamental domesticated variety, called koi. Between nibbles of dry food the duckling is simply sipping water — and not feeding the carps. They are trying to get some leftovers.
Sorry Mujin Am (22), known as Ohsako. It’s a nice video, but it’s not ‘The first case of spotbilled duck Anas poecilorhynchos feeding carp Cyprinus carpio‘.
Please note: carps do feed on ducklings.
[Editor's note, in case you didn't follow the very first link: Kees Moeliker is the Ig Nobel Prize-winning author of the study "The First Case of Homosexual Necrophilia in the Mallard Anas platyrhynchos (Aves: Anatidae)" C.W. Moeliker, Deinsea, vol. 8, 2001, pp. 243-7.]