What is the main ingredient of Bombay Duck?

The Bombay duck is an edible lizardfish that lives in the tropical parts of the Indo-Pacific.

https://en.wikipedia.org/wiki/Bombay_duck

In case you're wondering how a lizardfish became a duck, it's uncertain. The earliest recorded use of the phrase was in 1815, but did not apply to the fish in particular. It's been suggested that it may be a euphemism sort of like how Welsh rabbit is cheese toast and German duck is a sheep's head with onion.