This term often refers to the use of schooling fish to reduce the aggression or timid tendencies of some cichlids. Dither fish as well as schooling fish can include tetras, danios, and barbs. The intent is to use the fish as a sort of calming effect. The timid cichlids will watch the school swimming and pay attention to their behavior. As a result, if the school is calm, then the cichlid knows that the area is safe and will venture out. Thus the cichlid will become more outgoing and bold. The basics for choosing a dither fish are either to find a fish that moves fast enough to not be singled out or one that isn’t easily intimidated by a predator in the tank. 

Zebra danios make excellent dither fish. These fish are fast swimming and outgoing. They will encourage even the most shy fish to come out and swim.