While it’s clear that many fish seek out each other’s company, they don’t tend to nurture relationships with their shoal-mates.
Rabbitfish are a rare exception. These colourful coral-reef fish team up in pairs, often with members of the same sex, suggesting these partnerships are about more than reproduction.
Their preferred foraging technique of probing cracks and crevices in the reef for algae and sponges makes it hard to keep an eye out for predators while feeding.
So members of a pair take turns to eat while their partner remains out in the open to quite literally watch their backs.