Dither fish

The term dither fish refers to an arbitrary group of aquarium fish used by cichlid keeping aquarists to reduce innate timidity in some species of cichlids. Dither fish typically swim around the top of a tank and this behavior encourages more timid fish to relax and venture out more by reassuring them no predators are around. The technique relies on the ability of cichlids in an aquarium to use the behaviour of other fish species as a measure of environmental security. Good dither fish are typically schooling species, such as some Danio species, barbs and some tetra species.