The damselfish and its garden
In the threespot damselfish, a territory provides access to algae for food. By chasing approaching herbivores, the fish changes their movements and may limit local grazing.
A boundary revealed by chasing
A fish may use more space than it actively defends. Repeated chases can reveal which part it protects. How much effort that takes depends on the number of intruders and how they respond. A warning can sometimes avert physical contact.
A damselfish guards its eggs
In Chromis chromis, a male prepares a site where the female lays adhesive eggs. The eggs stay fixed in one place as they develop, and the male’s defence of the site protects the clutch during that period.
