The barracuda is a ray-finned fish known for its large size and fearsome appearance. Its body is long, fairly compressed, and covered with small, smooth scales. Some species can reach up to 2.1 m (6.9 ft) in length and 30 cm (12 in) in width. The barracuda is a saltwater fish of the genus Sphyraena, the only genus in the family Sphyraenidae, and is found in tropical and subtropical oceans worldwide. Barracudas are voracious, opportunistic predators, relying on surprise and short bursts of speed (up to 27 mph (43 km/h)) to overtake their prey.

Adults of most species are more or less solitary, while young and half-grown fish frequently congregate. Barracuda prey primarily on fish (which may include some as large as themselves). They kill and consume larger prey by tearing chunks of flesh.

Like sharks, some species of barracuda are reputed to be dangerous to swimmers. Barracudas are scavengers, and may mistake snorkellers for large predators, following them in hopes of eating the remains of their prey. Swimmers have been reported being bitten by barracuda, but such incidents are rare and possibly caused by poor visibility. Large Barracuda can be encountered in muddy shallows on rare occasion. Barracudas may mistake things that glint and shine for prey. One incident reported a barracuda jumping out of water and injuring a kayaker,but a marine biologist at the University of Florida said the type of wound appeared to have rather been caused by a houndfish.

Handfeeding or touching large barracuda in general is to be avoided. Spearfishing around barracudas can also be dangerous, as they are quite capable of ripping a chunk from a wounded fish thrashing on a spear.

Diamond rings and other shiny objects have been known to catch their attention and resemble prey to them. Caution should be taken when swimming near mangrove coastlines by covering or removing such items.