Monogamy is not common among fish. However, in several species of Butterflyfish the male and female stay together all the time. Often you see Red Sea bannerfish or Masked butterflyfish moving slowly about together.
Butterflyfish are easy to recognise and colourful species. They can be found in tropical Waters all over the World.
It is not all the butterfly species that go in pairs – at least not all the time. E.g. the Red Sea raccoon butterflyfish form groups or may be in pairs.
There are other species that usually are in pairs .e.g. the Stellate rabbitfish (above, or you find it in the Hide in the dark section of the book). – and you might also see other species in pairs. But it may just be two that tag along together, and it could as well be three or four fish in small groups – e.g. the trevallies or triggerfish. The Red Sea anemonefish (above) may also be two together, but could also be more fish together in an anemone …