Hmmm, I got in contact with my former professors about this and yeah, aromulus there is quite right. Ciguatera is the real culprit - the microscopic algae that thrives on the fish's body. I dunno why they find baracudas as good host.

When people ingest the fish that has ciguatera, they get poisoned by its (algae's) toxins.

Marine finfish most commonly implicated in ciguatera fish poisoning include the groupers, barracudas, snappers, jacks, mackerel, and triggerfish. Many other species of warm-water fishes harbor ciguatera toxins. The occurrence of toxic fish is sporadic, and not all fish of a given species or from a given locality will be toxic.
And ciguateras usually thrive in lower latitudes (near and below equator) thus in the northern hemisphere there is very little of ciguatera poisoning reports...as ciguateras, a kind of dinoflagellate (hope I don't bore you guys with jargons here) bloom (they are plants remember?) - ciguateras bloom usually during summer months when the ocean is warm....

my 2 cents there...