National Fish of Pakistan is:

This question tests general knowledge about national symbols.

• "Mahseer" is the correct answer. The Mahseer, specifically the Golden Mahseer (Tor putitora), is officially recognized as the National Fish of Pakistan. It is a significant freshwater fish species found in the rivers and lakes of the region, valued for its ecological importance and as a game fish.
• "Blue Marlin" is a distractor; it is a large oceanic fish, not native to Pakistan's freshwater systems and not designated as its national fish.
• "Hogfish" is a distractor; these are marine fish primarily found in the Atlantic Ocean and are not associated with Pakistan's national symbols.
• "Flounder" is a distractor; flounders are a type of flatfish found in various marine and estuarine environments globally, but they are not Pakistan's national fish.