Great barracuda are sometimes seen with small remoras attached. Interestingly, I never saw a remora on a barracuda while working in the Turks and Caicos Islands, whereas in aggregations in the Florida Keys I found it quite a common sight. One thing that I have seen in both the Florida Keys and Turks and Caicos Islands has been schools of horse-eye jacks and other carangids forming behind and following a single large barracuda, though the association never (in my experience) persists for long. Often, barracuda are shadowed by smaller jacks, like the bar jack. I've seen similar following behavior in other barracuda species that I observed in Papua New Guinea, including by many triggerfishes that seemed to be trying to join a barracuda school and by groups of rainbow runners (Elegatis bipinnulata) and bigeye trevally that were at least temporarily associated with blackfin barracuda.

Donald de Sylva (who published a monograph on great barracuda life history and systematics in 1963) has noted that he had not seen sharks and great barracuda together even though they occurred in the same habitat — other stories persist that indicate some kind of avoidance relationship between the two types of predators. Perhaps it is some variant of the Chinese adage that says two tigers can not share the same mountain, a principle long-ago recognized by ecologists to apply equally to a wide variety of natural systems. On the other hand, I have often seen barracuda and shark together and on one occasion saw a school of ten large barracuda (including, I believe, a highly territorial barracuda) form behind a 5-m length great hammerhead shark, swimming off into the distance with it. In Papua New Guinea, I have often seen barracuda in the presence of sharks, including an aggregation of 30 or more gray reef sharks, to which the barracuda seemed to pay no particular attention. Persistent stories that I get from recreational divers, however, reinforce de Sylva's note that barracuda and sharks don't seem to noticeably co-occur in at least some areas.

Any predator on the adult great barracuda would have to be large and very swift in its actions — to the best of my knowledge, only dolphins and tuna, both of which possess these necessary attributes, have been identified as occasional partakers of great barracuda. A fast and lucky shark may also be capable of taking an adult barracuda.

Cleaning symbiosis is one example of an association in which barracuda are often seen, and many barracuda appear almost addicted to the attentions of tiny cleaner fishes.