The term dither fish refers to an arbitrary group of aquarium fish, commonly used by aquarists, to help reduce innate timidity and aggression as well as to promote normal social behaviour in the other fish housed within the same aquarium. Dither fish help reduce anxiety of some nervous species of fish by allowing the fearful species to see that it is safe to leave cover and eat the food that has been given to them. Commonly used dither fish are typical schooling species, such as some Danio, barb and tetra species, and are most often used in cichlid tanks. Dither fish are typically fish that swim around the top of a tank, a behavior that reassures more timid fish that no predators are nearby, and are found naturally in the same habitat as the other fish in the aquarium, thereby encouraging them to relax and engage in normal behaviour. This technique relies on the ability of cichlids in an aquarium to gauge environmental security by observing the behaviour of other fish species.
- Ser JR, Roberts RB, Kocher TD (February 2010). "Multiple interacting loci control sex determination in lake Malawi cichlid fish". Evolution; International Journal of Organic Evolution. 64 (2): 486–501. doi:10.1111/j.1558-5646.2009.00871.x. PMC 3176681. PMID 19863587.
- Barlow GW (1968). "Dither—a way to reduce undesirable fright behavior in ethological studies". Z. Tierpsychol. 25 (3): 315–318. PMID 5684153.
- Stevens, C. H.; Croft, D. P.; Paull, G. C.; Tyler, C. R. (2017-07-09). "Stress and welfare in ornamental fishes: what can be learned from aquaculture?". Journal of Fish Biology. 91 (2): 409–428. doi:10.1111/jfb.13377. hdl:10871/27855. ISSN 0022-1112. PMID 28691234.
- Loiselle PV (November 1979). "On dither fish". Freshwater and Marine Aquarium Magazine: 30–34, 76–79.