Concept:Hilsa is a well-known fish species designated as the national fish of Bangladesh.
Explanation:Hilsa, also called Ilish, is an anadromous fish that lives in the sea but migrates to freshwater rivers to breed.
It is widely found in the Bay of Bengal and is crucial to Bangladesh's economy, contributing about 10% of its total fish production.
The fish holds cultural and economic importance in Bangladesh, where it is officially recognised as the national fish.
In India, Hilsa is the state symbol of West Bengal and Tripura, but not the national fish.
The national aquatic animal of India is the Gangetic dolphin, not Hilsa.
Pakistan and Nepal do not have Hilsa as their national fish.
Answer:Option C: Bangladesh.