Hawaiian Dascyllus, or damselfish, unique to local waters
One of the questions frequently asked by keiki visiting an aquarium is “where’s Nemo?”
This vibrantly orange-and-black fish with rounded fins is called a clownfish and is a member of the family Pomacentridae. To some children’s dismay, the not-so-funny clownfish do not inhabit Hawaiian waters, but a close relative, the damselfish, or Hawaiian Dascyllus (Dasyllus albisella), do.
Hawaii is home to 17 of the 325 known species of damselfish. The endemic Hawaiian Dascyllus is also a member of the family Pomacentridae. It is unique to Hawaiian waters and found nowhere else on the planet.
This fish is one of a few who have the Hawaiian name ‘alo’ilo’i, which not only refers to their small mouths, but can also mean “bright” or “sparkling” – aptly named for the way their coloration creates a shimmering appearance.
As juveniles, damselfish have a large white spot on either side of their bodies and a prominent spot on their foreheads. As the fish grows, the spot fades into more of a gray patch and the forehead spot disappears.
During spawning, a female will lay eggs in the sand while being pursued by a male, who will follow close behind her, attempting to fertilize the eggs. During this process, the black on both male and female will fade and both fish will turn almost white for reasons not entirely understood.
Various types of fish are capable of lightening or darkening in appearance as a warning message or camouflage, and so perhaps this is why the Hawaiian Dascyllus can do the same. It is also possible that the high contrast pattern seen on juvenile damselfish is a warning of their aggressive nature.
Despite their small size – with many fewer than 6 inches – damselfish are not shy about defending an algae-rich territory against surgeonfish or keeping other predators away from their eggs. When alarmed, damselfish will chirp loudly and dart towards the source of the alarm. People who have attracted the aggression of this tiny fish may feel it before they see it, as damselfish have been known to even nip at the fins of divers.
Like their clownfish cousins, Hawaiian Dascyllus will seek refuge amongst the soft tentacles of the stinging sand anemone (Heteractis malu) during their juvenile stage. Living in coral, highly populated with other animals, may be too risky for such a small fish, so living within the protection of the sting of an anemone is a greater defense against any possible predator. For the sand anemone, the aggressive little fish will provide some protection too.
Both the Hawaiian Dascyllus and the more popularly known clownfish have formed an immunity to the deadly sting of the anemones.
But remember, when snorkeling or diving in Hawaii, you won’t find Nemo here. What you may run into are a few of the “sparkling” black-and-white damselfish – the adults, darting in and around the arms of branching coral and feeding on plankton as it drifts by, or the juveniles hiding in sea anemones, waiting for an opportune moment to nip at your fins.
* Erin Iberg is the community education manager at Maui Ocean Center. “Ka Mo’olelo Moana,” or “The Ocean Story,” is a monthly column submitted by the center. It is open from 9 a.m. to 5 p.m. daily in Maalaea. For more information, call 270-7000.