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Damselfish [Extra Quality]

Damselfish are those within the subfamilies Abudefdufinae, Chrominae, Lepidozyginae, Pomacentrinae, and Stegastenae within the family Pomacentridae.[1][2] Most species within this group are relatively small, with the largest species being about 30cm (12 in) in length.[3] Most damselfish species exist only in marine environments, but a few inhabit brackish or fresh water.[3] These fish are found globally in tropical, subtropical, and temperate waters.[4]


Many species live in tropical rocky or coral reefs, and many of those are kept as marine aquarium pets. Their diets include small crustaceans, plankton, and algae. However, a few live in fresh and brackish waters, such as the freshwater damselfish, or in warm subtropical climates, such as the large orange Garibaldi, which inhabits the coast of southern California and the Pacific Mexican coast.

The domino damselfish D. albisella spends the majority (greater than 85%) of its daytime hours foraging. Larger individuals typically forage higher in a water column than do smaller ones. Damselfish of all sizes feed primarily on caridea and copepods. Males have relatively smaller stomach sizes during spawning season compared to females due to the allocation of resources for courtship and the guarding of nests. When current speeds are low, the damselfish forages higher in a water column where the flux of plankton is greater and they have a larger food source. As current speeds increase, it forages closer to the bottom of the column. Feeding rates tend to be higher when currents are faster. Smaller fishes forage closer to their substrates than do larger ones, possibly in response to predation pressures.[5]

There are many examples of resource partitioning and habitat selection that are driven by aggressive and territorial behaviors in this group. For example, the threespot damselfish S. planifrons is very defensive of its territory and is a classic example of extreme territoriality within the group.[6] One species, the dusky damselfish S. adustus spends the majority of its life within its territory.[7]

In the species S. partitus, females do not choose to mate with males based on size. Even though large male size can be advantageous in defending nests and eggs against conspecifics among many animals, nest intrusions are not observed in this damselfish species. Females also do not choose their mates based upon the brood sizes of the males. In spite of the increased male parental care, brood size does not affect egg survival, as eggs are typically taken during the night when the males are not defending their nests. Rather, female choice of mates is dependent on male courtship rate. Males signal their parental quality by the vigor of their courtship displays, and females mate preferentially with vigorously courting males.[9][10]

Male damselfish perform a courtship behavior called the signal jump, in which they rise in a water column and then rapidly swim back downward. The signal jump involves large amounts of rapid swimming, and females choose mates based on the vigor with which males do so. Females determine the male courtship rates using sounds that are produced during signal jumps. As the male damselfish swims down the water column, it creates a pulsed sound. Male courtship varies in the number and rates of those pulses.[11]

In the beaugregory damselfish S. leucostictus males spend more time courting females that are larger in size. Female size is significantly correlated with ovary weight, and males intensify their courtship rituals for the more fecund females. Research has shown that males that mate with larger females do indeed receive and hatch greater numbers of eggs.[12]

The male cortez damselfish, S. rectifraenum, is known to engage in filial cannibalism. Studies have shown it typically consumes over twenty-five percent of its clutches. The males generally consume clutches that are smaller than average in size, as well as those that are still in the early stages of development. Female cortez damselfish tend to deposit their eggs with males who are already caring for early-stage eggs, rather than males with late-stage eggs. This preference is seen particularly in females that deposit smaller-sized clutches, which are more vulnerable to being consumed. For the males, filial cannibalism is an adaptive response to clutches that do not provide enough benefits to warrant the costs of parental care.[15]

Widespread throughout warm and temperate seas in the World, damselfish are small and generally colorful fish. They are very easy to observe: they often are the first fish you spot after entering the water.

Other common damselfish are the whitetail dascyllus (found in most of the Indo-Pacific area), the beau gregory (endemic to the Caribbean) and the Garibaldi damselfish (commonplace along the Californian coast).

A longfin damselfish patrols its algae garden off the coast of Bonaire. Damselfish kill a section of the coral, and then wait for algae to grow in the dead spot. On this coral, only a few live sections remain. Henry DeBey hide caption

"They're little feisty guys," Vermeij says. "There are rainbow parrot fish, almost a meter long, and this damselfish that's not much bigger than a goldfish just comes out. This parrotfish is aiming at feeding in that guy's little meadow. And the little damselfish just comes out and scares that thing away. They're aggressive as hell."

Seen from above, a three-spot damselfish's algae garden covers much of this coral. The identification tag, top, allows researchers to track and monitor the site. Henry DeBey hide caption

Graysbys, like this one, normally prey on damselfish and help keep their populations in check. But as graysby populations decline due to overfishing, damselfish numbers are increasing. Henry DeBey hide caption

As a result, the damselfish population has boomed. As Vermeij tells the story, Henry DeBey listens in. He's a graduate student at Yale University. He's here on Bonaire to get a better handle on the damselfish story. And he says it turns out that one predatory fish in particular goes after the damselfish. It's called a graysby.

As a result, graysby populations have been in severe decline along Bonaire's reef. DeBey and a fellow graduate student from Yale are here to quantify just how much graysby overfishing has led to a surge in damselfish and their algae gardens. They want to provide ironclad evidence that the marine park manager can use, to give local fishermen a Hobson's choice.

And while algae form a natural ecosystem, it's not nearly as interesting and diverse as a coral reef. And it's the thriving coral reef that attracts divers to Bonaire from far and wide. They keep the local economy humming. So there's a lot at stake, in the story of the little damselfish.

The discovery, made by Giacomo Bernardi, an ichthyologist at the University of California, Santa Cruz, and his colleagues suggests that Altrichthys damselfish are both the victims and perpetrators of brood parasitism.

One morning, Bernardi and his team were observing a pair of Altrichthys when a large school of damselfish larvae drifted onto the reef. The school contained tens of thousands of baby damselfish, all in search of a reef to settle on. Over the next few days, the researchers observed predators decimate the defenseless school. The only fish that survived the onslaught, Bernardi says, were ones that managed to sneak their way into an Altrichthys brood.

They're not as aggressive as most other damselfish species and should not be kept with very aggressive fish. These damsels can be aggressive towards smaller fish in the damselfish family but tend to be peaceful towards larger species. They do well in small to medium sizes groups and are sure to bring a splash of color to the mid level of your aquarium.

Back in the day before fishless cycling was common practice, the Damselfish was the fish you would use to cycle a saltwater tank because they could tolerate levels of ammonia, nitrite, and nitrates that would kill off many other saltwater fish. Of course, nowadays one should never consider cycling with damselfish. However, they are extremely hardy in a tank and are a very forgiving fish for a novice.

The Azure damselfish species is the most mild-mannered of the group. It has a wonderful disposition in the group and has rarely caused disruptions in aquariums. It is the best Damselfish to choose if you are considering one that is blue. In larger tanks, they have been kept in groups. It is as of the date of this post, the only Damselfish of the 4 that is available as tank bred.

Contrary to common belief that all Damsels are evil, we have listed several damselfish that are compatible in a reef community tank. As long as you add them last and pick the correct species of fish to mix them with, you should have a little blue marine fish that you can enjoy! Thanks for reading!

By the century's end, many tropical seas will reach temperatures exceeding most coral species' thermal tolerance on an annual basis. The persistence of corals in these regions will, therefore, depend on their abilities to tolerate recurrent thermal stress. Although ecologists have long recognized that positive interspecific interactions can ameliorate environmental stress to expand the realized niche of plants and animals, coral bleaching studies have largely overlooked how interactions with community members outside of the coral holobiont shape the bleaching response. Here, we subjected a common coral, Pocillopora grandis, to 10 days of thermal stress in aquaria with and without the damselfish Dascyllus flavicaudus (yellowtail dascyllus), which commonly shelter within these corals, to examine how interactions with damselfish impacted coral thermal tolerance. Corals often benefit from nutrients excreted by animals they interact with and prior to thermal stress, corals grown with damselfish showed improved photophysiology (Fv /Fm ) and developed larger endosymbiont populations. When exposed to thermal stress, corals with fish performed as well as control corals maintained at ambient temperatures without fish. In contrast, corals exposed to thermal stress without fish experienced photophysiological impairment, a more than 50% decline in endosymbiont density, and a 36% decrease in tissue protein content. At the end of the experiment, thermal stress caused average calcification rates to decrease by over 80% when damselfish were absent but increase nearly 25% when damselfish were present. Our study indicates that damselfish-derived nutrients can increase coral thermal tolerance and are consistent with the Stress Gradient Hypothesis, which predicts that positive interactions become increasingly important for structuring communities as environmental stress increases. Because warming of just a few degrees can exceed corals' temperature tolerance to trigger bleaching and mortality, positive interactions could play a critical role in maintaining some coral species in warming regions until climate change is aggressively addressed. 041b061a72


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