They are predominantly blue to gray in colour and have a characteristically large dorsal fin known as the sail, which often stretches the entire length of the back.

Another notable characteristic is the elongated rostrum (bill) consistent with that of other marlins and the swordfish, which together constitute what are known as billfish in sport fishing circles.

Sailfish live in colder pelagic waters of all Earth's oceans, and hold the record for the highest speed of any marine animal.

[16][17] Sailfish usually attack one at a time, and the small teeth on their bills inflict injuries on their prey fish in terms of scale and tissue removal.

The underlying mechanism was termed proto-cooperation because it does not require any spatial coordination of attacks and could be a precursor to more complex forms of group hunting.

However, a possibility exists that sailfish with strong side preferences could become predictable to their prey because fish could learn after repeated interactions in which direction the predator will hit.

[19] The injuries that sailfish inflict on their prey appear to reduce their swimming speeds, with injured fish being more frequently found in the back (compared with the front) of the school than uninjured ones.

The size of their predators increases as they grow, and adult sailfish are not eaten by anything other than larger predatory fish like open ocean shark species and orcas.