Barracudas are primarily fish eaters, preying on such smaller fishes as mullets, anchovies, and grunts. They are esteemed as sport fishes, and the smaller forms are also valued as food. In certain seas, however, they may become impregnated with a toxic substance that produces a form of poisoning known as ciguatera. Barracudas are often regarded as bold and inquisitive, and large ones are regarded as fearsome fishes, potentially dangerous to humans. The threat, though probably exaggerated, is real; the great barracuda is known to have been involved in attacks on swimmers.