The whole concept of organisms “in captivity” is bizarre and, frankly, pretty useless. I was recently told that “The best practice is generally to mark as “captive” if the location of the observation isn’t the collection itself - the organism was taken captive and moved to the location because of a human’s intention (not the organism’s own movement or a natural process).”
In other words, anything captured in a dredge, or a plankton net or a seine is considered a “captive” because it has been moved by human agency. Even a butterfly net would be iffy. Tiny organisms that have to be taken to a laboratory to be examined under a microscope would also be “captives.”
That said the situation described by the OP here doesn’t involve an organism pictured obviously in captivity (rather the opposite), so it’s probably best to keep the thread focused on that situation.