The black marlin is found in the Indian, Indo-Pacific, and Pacific Oceans where the waters are tropical and subtropical. The black marlin is one of the largest bony fish and one of the fastest in the world.
Even though they are known as black marlin, most of their body is silver with a deep, rich, dark, blue on their back. The female black marlin are the famous “granders” that get over 1,000lbs. The males are usually no more than 200lbs at best.
Some anglers have trouble distinguishing between a blue and a black marlin, but once you’ve looked at a few, you will notice some striking differences. The bill and the dorsal fin on a black marlin are shorter than that of a blue marlin. Overall, the body of a black is more stocky and solid.
If you still have a hard time determining whether it’s one or the other, the easiest way to identify a black is by the pectoral fin. The black marlin is the only marlin species that cannot fold their pec fin against their body. As they develop and mature, the pectoral fin becomes more rigid and by the time they reach a weight of roughly 150lbs, the fin is unable to fold in against the body. The fins can still be tilted backwards to reduce drag when cutting through the water.
You will find these monsters swimming over major underwater drop offs such as the edges of deep-water reefs where there are upwelling that attract an array of fish and bring fresh oxygen and minerals to the surface. These make a great place to catch, and troll live or dead baits and have the best chance for a bite.