Clownfish became every child’s favourite fish (and also mine!) following the release of Disney’s ‘Finding Nemo’.
There are 28 known species of clownfish. The Red Sea Anemonefish (amphiprion bicinctus), which is native to the Red Sea, lives in a symbiotic (mutually beneficial) relationship with the anemone.
The clownfish performs an elaborate dance with an anemone before taking up residence, gently touching its tentacles with different parts of their bodies until they are acclimated to their host. A layer of mucus on the clownfish’s skin makes it immune to the fish-eating anemone’s lethal sting.
The clownfish feeds on small invertebrates, which could otherwise potentially harm the sea anemone, and the faecal matter from the clownfish provides nutrients to the sea anemone. Clownfish are omnivores and eat live food such as algae, plankton, molluscs and Crustacea with algae accounting for around 20 to 25 percent of its diet. It has also been suggested that the activity of the clownfish results in greater water circulation around the sea anemone. In addition to providing food for the clownfish, the sea anemone also provides safety due to its poison.
Clownfish live in small groups inhabiting a single anemone. The group consists of a breeding pair, which cohabits with a few non-reproductive, “pre-pubescent”, and smaller male clownfish. When the female dies, the dominant male changes sex and becomes the female, a change which is irreversible. This life history strategy is known as sequential hermaphroditism. Because clownfish are all born as males, they are protandrous hermaphrodites. This phenomenon is also found in other species of fish in the Red Sea.
Clownfish lay eggs on any flat surface close to their host anemones. They spawn around the time of the full moon and the male parent guards them until they hatch about 6 to 10 days later, typically 2 hours after dusk.
This article by Sarah Wright was originally published in 2010.