Why is the Bombay Duck considered a unique species?

The Bombay Duck is recognized as a unique species primarily due to its distinctive noise. This fish, which is primarily found in the waters of the Arabian Sea and the Bay of Bengal, produces a sound that is often described as a 'quack' or a 'croak.' This unusual noise is a notable characteristic that sets it apart from many other fish species, making it a subject of interest among marine biologists and researchers.

The other aspects mentioned, while interesting, do not accurately reflect the traits that define the Bombay Duck. For instance, it is not bioluminescent, does not routinely swim upside down, nor is it particularly noted for forming large schools compared to other species in its habitat. The uniqueness of the Bombay Duck lies in its vocalizations, which play an important role in communication and potentially in mating behaviors within this species.