What is the typical habitat of the Bombay Duck?

The Bombay Duck, also known as the Bombil, is predominantly found in coastal shallow waters. This fish species thrives in brackish environments where freshwater from rivers meets saltwater from the ocean, allowing it to adapt to varying salinities. Coastal shallow waters provide an ample supply of food and are rich in nutrients, which are essential for the Bombay Duck’s feeding habits, as it primarily eats small invertebrates and plankton.

The other options relate to habitats that are not typical for this species. Coral reefs offer complex structures which are not characteristic of the Bombay Duck's preferred ecological niche. River estuaries, while somewhat appropriate, usually do not encompass the range where the Bombay Duck is most frequently seen. Deep ocean waters are too expansive and lack the favorable conditions and food sources that coastal areas provide, making them unsuitable for the Bombay Duck's lifestyle. Thus, the habitats closely associated with its biological needs and behavior are indeed the coastal shallow waters.