There are a number of benefits to living in large groups. For one, it provides safety in numbers. Predators are less likely to attack a large group of fish than they are to attack a single fish. Additionally, living in a group can help guppies to find food and mates. Guppies that live in groups are more likely to be successful in finding food than those that live alone, and they are also more likely to attract mates.
Overall, living in large groups is beneficial for guppies. It provides them with safety, food, and mates, and it helps them to interact socially.