Cherry barbs are a peaceful and social species of fish that do best in groups. In the wild, they can be found living in large schools numbering in the hundreds. While it's not necessary to keep that many cherry barbs in an aquarium, they should still be kept in groups of at least six. This will allow them to feel secure and help reduce aggression levels. Cherry barbs are also relatively active fish and need plenty of space to swim. A 20-gallon tank is the minimum size that should be considered for a group of six cherry barbs.