The blue marlin is a member of the Istiophoridae Family, also known as Billfish. In Latin America, they are known as Marlina Azul. Some scientists believe that the Pacific Blue Marlin is its own species, but currently, the genus Markaira is known globally to represent both Pacific and Atlantic Blue Marlin.    
They are known for their round, portly, shaped body. They are solid muscle with a compressed body compared to the more agile striped or white marlin. There are many differences between a striped and a blue marlin, but the most obvious is the difference in the dorsal fin.
On a blue marlin, the dorsal fin is pointy, whereas on a striped marlin, the dorsal fin is rounded on the tip. Both have long rows of stripes and spots. The blue marlin is covered with long, thick bony scales and their pectoral fin folds against the body (unlike a black marlin).
The Blue Marlin is found offshore and in richly oxygenated, blue water. Known as a pelagic species, they are usually found swimming above the thermocline where the water tends to be warmer.
These fish are migratory and will travel in schools towards the equator during the winter months to avoid cooler temperatures and green water. As they grow into giants, they become more solitary, while the younger ones can be found moving in schools.  
Blue Marlin are known as a dimorphic species, meaning that the females are larger than the males. A male, blue marlin will be full grown around 300 lbs. whereas a female can exceed 2,000 lbs. and over 14 ft in length!
Their diet consists mainly of dorados, tuna, and other types of mackerel. Occasionally, they have been known to feed on squid too, but not as common. They are incredibly aggressive feeders and not only use their bill to slash, but also stab their prey.
The Blue Marlin is considered an apex predator. They are preyed upon by great white sharks and makos, however their greatest threat is man. They have lifespans of twenty-seven years for females and eighteen years for males, but are heavily targeted by fishermen and harvested before maturity. Using catch and release practices, we can do our part to make sure we keep these giants around for years to come.