European barracuda and blue fish: - "Atlantic horse encircling a fodder ball of Mackerel"

This Atlantic horse Mackerel is making a bat ball. The open ocean is without hiding the place between the celestial, coral or coastal rocks. They will gather together at least to expose the personal fish.

image & source https://www.bing.com/search?q=bait+ball&FORM=HPVSBS&filters=HpDate%3a%2220180501_1830%22

It is surrounded by hunters like barracuda and Bluefish when seen here. Where does this idea come out of security in numbers? This bait ball will protect the smallest fish.