Damselfish are small colourful marine fishes. You can find them in most of the warm tropical seas. So, they thrive best in the shallow waters of the Atlantic and Indo-Pacific Ocean.
Marine biologists believe there are more than 250 different saltwater damselfish species. But, the majority of the species fall under the scientific classification of Pomacentridae.
In fact, the damselfish family has a subspecies. It includes clownfish (or anemonefishes) from the subfamily genus Amphiprioninae and Premnas. All these fishes are conspicuous by their bright colouring.
The deep-bodied, lively, schooling fish can grow to a whopping 36 cm long (14 inches) darting around in their wild habitat. Damsels are territorial in nature. They often display a surprisingly aggressive, angry, behaviour – for a relatively small tropical marine fish.
Some of the most brightly-colored species will display shades of orange-yellow, red, and blue. Most have forked tails like their cichlid relatives.
One of the most surprising damselfish facts is that, despite being broadly marine animals, a select few of the damselfish family actually inhabit lower stretches of fresh water rivers.
In fact, coral reef scuba divers and shallow water snorkelers often ignore saltwater damselfish (also called Demoiselle). It may be because they see some of the species as being a little drab in pigmentation.
But, spend time observing and studying this feisty and fastidious vertebrate. You are likely to find the darting damselfish species much more interesting and entertaining than you might expect.
Damselfish Species Habitat
The tiny species of small, brilliant colored tropical marine fishes are ‘notoriously’ pugnacious. They are extremely territorial and protect their home turf with vigor on the sandy seabed.
Often, you will see them lunging at much larger fishes. It is not uncommon for them to ‘attack’ scuba divers – especially if they feel threatened.
This belligerent behavior is how most of the small reef fish guard and defend their personal patch of algae or anemone. It creates a shelter for its eggs.
Damselfish Facts: The Indo-Pacific’s Dusky Farmerfish – pictured below – selectively filter their chosen habitat. They grow and graze on only one particular species of algae. They defend their small circular gardens of hue from other fishes. Somewhat interestingly though, the algae cannot actually survive without the presence of these dusky damselfish.
Male Damselfish Courtship Behavior
The males exhibit a mesmerizing display during their courtship cycle. They try to attract females to their nest by jetting up and down from their seabed territory.
Even though the courtship displays are more common at dawn, it is not an aggressive behavior. It is more of a fish flirtation aimed towards any egg-depositing females in the area.
It is the male of the species which take on the role of egg tending once the spawn gets deposited in the nest. They tend the eggs and oxygenate them by periodically fanning them with their fins.
Sequential Hermaphroditism Facts
Damselfish exhibit a common fish behavior of sequential hermaphroditism. This means they can change genders – which is extremely rare among vertebrates. Depending on the fish species, sequential hermaphroditism may be protandrous (males change to females) or protogynous (females change to males).
Damselfish Facts: The two-stripe damsel (Reticulated dascyllus) is a protogynous hermaphrodite. They will change their sex gender from female to male when a male is no longer available for mating.
Identifying Saltwater Damselfish
Many of the different fish families and classifications are a challenge to identify. This is especially so for those who are unfamiliar with fish traits and their colours.
But, fish identification of the juvenile species is easier for most learners. This is because the young are often brilliant in coloration.
In fact, damselfish tend to become less colorful and more drab as they mature. They then exhibit sexual dimorphism – a distinct difference in size or appearance between the sexes. Thus, you need to know all the maturing stages to be correct in identifying damsels.
Interesting Facts about Damselfish
- The colour of juvenile damselfish is different from mature adult fishes. Juveniles often have spots which may darken as they mature.
- Many of the species mature around three years and some grow to 30 cm – although most are around 15 cm long.
- They thrive best in shallow coral reefs, sea grass, and sheltered mangroves. These are the areas where they can feed on algae and zooplankton.
- Some genus make a strange clicking noise – almost purring – during the courtship season. This ritual happens most often from spring to summer.
- Females lay around 20,000 tiny oval eggs. They vigorously defend their sandy seabed territory during the spawning season.
The images show the yellowtail blue damselfish [Chrysiptera parasema] and the yellowtail damselfish.
Note: The relatively rare domino damselfish species is one of the species found in shallow waters around coral island formations. The marine life section has more facts and information about creatures that live in the underwater world.