The fastest fish in the ocean is the black marlin. Capable of reaching speeds up to 82 miles per hour (132 km/h), the black marlin is among the fastest and most agile fish in the sea. Known for their long, slender bodies and powerful bills, they are highly sought after by sport fishermen. Their speed and acrobatic leaps make them a thrilling catch. Black marlins are primarily found in tropical and subtropical regions, often inhabiting deep offshore waters.