The bluefin trevally is a fast swimming, mainly piscivorous predator which shows a wide range in hunting techniques.
Two studies of adult fish in Hawaii found fish to be the dominant food type in the species, making up over 95% volume of the stomach contents by weight.
Here the main fish selected were small reef dwellers, with fish from the families Labridae, Mullidae, Scaridae and Priacanthidae being the most common.
Despite the preference of several families, bluefin trevally do take a very wide variety of fish in small amounts, including various species of eel.
The species appears to have a preference for fish of a specific size, which depends on its own length and age.

Cephalopods (mainly octopus or squid) and a wide array of crustaceans are also taken in smaller quantities, with shrimps, stomatopods and crabs being the most common.
The diet of juveniles in Hawaiian and South African estuaries has also been determined, with these younger fish having a more crustacean based diet than the adults.
In Hawaii, crustaceans make up 96% of the gut contents numerically, with tanaids and isopods dominating the diet, while fish (mainly gobioids) only make up 4% numerically.
Juveniles less than 170 mm in South African estuaries feed predominantly on mysids and paenid prawns, before shifting to a more fish based diet at larger sizes.
Small fish are able to effectively filter these small crustaceans from the water, while adults are not.
In both cases, a transition to a more fish based diet with age was found to occur, although the length at which this transition occurred varied between location.
The diet overlap with the similar C. ignobilis is low in the Hawaiian Islands, suggesting there is some separation of feeding niches.
 Calculations suggest each individual bluefin trevally consumes around 45 kg of fish per year on average, making it one of the most effective predators in this habitat.

The bluefin trevally displays a remarkable array of hunting techniques, ranging from midwater attacks to ambush and taking advantage of larger forage fish.
The species is reported to hunt during the day, particularly at dawn and dusk in most locations; however it is known to be a nocturnal feeder in South Africa.
The bluefin trevally hunts both as a solitary individual and in groups of up to 20, with most fish preferring an individual approach.
In groups, these fish will rush their prey, and disperse the school, allowing for isolated individuals to be picked out and eaten, much in the way the related species, giant trevally have been observed to do in captivity.
In some cases, only one individual in a group will attack the prey school.
Where the prey is schooling reef fishes, once the prey school has been attacked, the trevally chases down the prey as they scatter back to cover in the corals, often colliding with coral as they attempt to snatch a fish.
 While hunting in midwater, fish swim both against and with the tide, although significantly more fish hunt when swimming with the tide (i.e. 'downstream'), suggesting some mechanical advantage is gained when hunting in this mode.
Another method of attack is ambush; in this mode the trevally change their colour to a dark pigmentation state and hide behind large coral lumps close to where the aggregations (often spawning reef fish) occur.
Once the prey is close enough to the hiding spot, the fish ram the base of the school, before chasing down individual fish.
These dark fish in ambush mode vigorously drive away any other bluefin trevally that stray too close to the aggregation.
Ambushes have also been observed on small midwater planktivorous fishes are moving to or from the shelter of the reef.
In many cases, the species uses changes in the depth of the reef such as ledges to conceal its ambush attacks.
Bluefin trevally also enter lagoons as the tide rises to hunt small baitfish in the shallow confines, leaving as the tide falls.
The species is also known to follow large rays, sharks and other foraging fish such as goatfish and wrasse around sandy substrates, waiting to pounce on any disturbed
The bluefin trevally is a fast swimming, mainly piscivorous predator which shows a wide range in hunting techniques. Two studies of adult fish in Hawaii found fish to be the dominant food type in the species, making up over 95% volume of the stomach contents by weight. Here the main fish selected were small reef dwellers, with fish from the families Labridae, Mullidae, Scaridae and Priacanthidae being the most common. Despite the preference of several families, bluefin trevally do take a very wide variety of fish in small amounts, including various species of eel. The species appears to have a preference for fish of a specific size, which depends on its own length and age. 
Cephalopods (mainly octopus or squid) and a wide array of crustaceans are also taken in smaller quantities, with shrimps, stomatopods and crabs being the most common. The diet of juveniles in Hawaiian and South African estuaries has also been determined, with these younger fish having a more crustacean based diet than the adults. In Hawaii, crustaceans make up 96% of the gut contents numerically, with tanaids and isopods dominating the diet, while fish (mainly gobioids) only make up 4% numerically. Juveniles less than 170 mm in South African estuaries feed predominantly on mysids and paenid prawns, before shifting to a more fish based diet at larger sizes. Small fish are able to effectively filter these small crustaceans from the water, while adults are not. In both cases, a transition to a more fish based diet with age was found to occur, although the length at which this transition occurred varied between location. The diet overlap with the similar C. ignobilis is low in the Hawaiian Islands, suggesting there is some separation of feeding niches.  Calculations suggest each individual bluefin trevally consumes around 45 kg of fish per year on average, making it one of the most effective predators in this habitat.
The bluefin trevally displays a remarkable array of hunting techniques, ranging from midwater attacks to ambush and taking advantage of larger forage fish. The species is reported to hunt during the day, particularly at dawn and dusk in most locations; however it is known to be a nocturnal feeder in South Africa. The bluefin trevally hunts both as a solitary individual and in groups of up to 20, with most fish preferring an individual approach. In groups, these fish will rush their prey, and disperse the school, allowing for isolated individuals to be picked out and eaten, much in the way the related species, giant trevally have been observed to do in captivity. In some cases, only one individual in a group will attack the prey school. Where the prey is schooling reef fishes, once the prey school has been attacked, the trevally chases down the prey as they scatter back to cover in the corals, often colliding with coral as they attempt to snatch a fish.  While hunting in midwater, fish swim both against and with the tide, although significantly more fish hunt when swimming with the tide (i.e. 'downstream'), suggesting some mechanical advantage is gained when hunting in this mode. Another method of attack is ambush; in this mode the trevally change their colour to a dark pigmentation state and hide behind large coral lumps close to where the aggregations (often spawning reef fish) occur. Once the prey is close enough to the hiding spot, the fish ram the base of the school, before chasing down individual fish. These dark fish in ambush mode vigorously drive away any other bluefin trevally that stray too close to the aggregation. Ambushes have also been observed on small midwater planktivorous fishes are moving to or from the shelter of the reef. In many cases, the species uses changes in the depth of the reef such as ledges to conceal its ambush attacks. Bluefin trevally also enter lagoons as the tide rises to hunt small baitfish in the shallow confines, leaving as the tide falls. The species is also known to follow large rays, sharks and other foraging fish such as goatfish and wrasse around sandy substrates, waiting to pounce on any disturbed
Bluefin trevally