Although aggressive and ferocious these eager hunters have accounted for only two human fatalities, one in 1947 and the other in 1957. Usually a barracuda attack leaves one with some serious lacerations, a well documented attack in 1960 resulted in 31 stitches.
They predominantly feed on various reef fish that they ambush by keeping still in a gully and then charging out biting the prey fish or a chunk out of a bigger fish. People diving or snorkeling on warm water reefs should be cautious of anything silver that flashes in the light as these fish will interpret it as a reef fish and likely to attack. Either leave your watch off or cover it when diving/snorkeling.
In 2011 there was an article describing a 5 to 6 ft (1.5 to 1.8 m) barracuda attack as follows:
“I noticed that my daughter had drifted about 10 or 15 feet away, and started to swim towards her. At that point there was stunning blow to my hand, but I never saw what hit me. It struck me that I must have hit a boat with my hand even though there was none near by, as the dive boat had drifted away while we were watching the barracuda. I lifted my hand out of the water and blood was pouring from it. My daughter said it was the barracuda that had attacked me. We began yelling as loud as we could, but the boat was about a quarter of a mile away; everybody was having lunch, and it took a long time- seemingly forever, before they took notice. I was afraid that the blood in the water would attract another attack and held my hand as high out of the water as I could. I never saw the finger again and imagine the barracuda ate it or spat it out when it turned out not to be fishy enough.
I never saw the attack, but Marina, who was facing me saw the entire thing. She said that the barracuda charged me from the bottom with its mouth open and that we both disappeared in a cloud of bubbles. She saw the barracuda charge me two more times in very rapid succession, each time seeing me vanish in cloud of bubbles, but I am certain that it only bit me once. “
– for the full story access via this link: https://www.undercurrent.org/blog/2011/01/04/barracuda-attack/
We know that attacks are not very common and that there is a risk of poisoning if one eats the fish. This is the ciguatera poisoning which finds its source in marine dinoflagellates that grow attached to marine algae. this algae is consumed by reef fish in small amounts but the Barracuda being the apex predator consumes many reef fish and becomes a ciguatera reservoir!
For this reason the US federal government has banned catching and selling of barracuda.
From a reproduction point of view, Barracuda become mature at 2 years and live for about 14 years. Females will spawn a few times in a breeding season and the fertilized eggs are left to drift in the ocean. She will typically lay between 5 000 and 300 000 eggs at a time with external fertilization occurring.
Some sources claim that the females could produce as much as 5 million eggs in a season!