Tiny (and one not so tiny) Terrors of the Sea: Damsels of the Genus Dascyllus by Steven Pro

The so-called Humbug Damsels of the genus Dascyllus are perennial favorites of beginning marine aquarists, and for good reason. They are tough little characters, readily available, inexpensive, attractive and able to withstand the unforgiving period of time most beginners spend on the marine aquarium learning curve. Sounds like the perfect fish, doesn't it? I have not yet mentioned their temperament. They happen to be exceptionally territorial, highly aggressive and totally fearless. These attributes make more experienced hobbyists avoid them. Even so, three species in this genus regularly make the top ten list of most frequently imported marine fishes.

Damsels, along with their relatives, the clownfishes, make up the family Pomacentridae. This family consists of 28 genera and 321 species (Fenner, 2001). The subfamily Chrominae consists of the genera Acanthochromis, Azurina, Chromis, and Dascyllus (Schultz, 2003). The first two genera are not generally kept in aquaria, but the other two are staple organisms in the marine ornamental trade. Note that these groupings are made on the basis of shared structural characteristics, not temperament. As anyone that has ever kept Chromis and Dascyllus can surely tell you, they do not behave the same. The genus Dascyllus has nine species, three of which are routinely offered for sale, another two that are available frequently, three available only occasionally, and one species I have yet to see ever offered for sale.

Dascyllus albisella:
The so-called Hawaiian humbug, besides being a native to Hawaiian waters, is also found at Johnston Islands, where it has been found living among branching corals (Pocillopora species) as well as some anemones (Marcanthia cookei). These fish are occasionally available and grow to a substantial length of five inches.

Dascyllus aruanus:
This is the extremely common Three-Stripe or White-Tail damsel (photo right). They are found throughout the Indo-Pacific region and are available in most any local fish store on any given day. They grow to almost four inches and are usually found living in and among Acropora stands in the wild.

Dascyllus carneus:
This species is only occasionally offered for sale, usually by the name Cloudy or Blue-Spot Dascyllus. They are found throughout the Indian Ocean where they associate with various branching corals. They are relatively small with a maximum length of less than three inches.

Dascyllus flavicaudus:
The Yellow-Tail humbug is another irregular offering from the Eastern Central Pacific; for instance, the Cook Islands. They are one of the larger species, growing to not quite five inches.

Dascyllus marginatus:
This species is called the Red Sea or Marginate damsel and, as the name implies, they come from the Red Sea as well as the Gulf of Oman, where they grow to barely over two inches long as adults and hide among Stylophora, Acropora and Porites corals.

Dascyllus melanurus:
The Four-Stripe or Black-Tail humbug is another species that can be found on any given day at a majority of fish stores and wholesale facilities. Their range includes all of the Western Indo-Pacific and they grow to about three inches. They are usually found near Acropora species.

Dascyllus reticulatus:
The Reticulate humbug (below) is sometimes called the Two-Stripe humbug, although its second stripe is not always very sharp at all. The first stripe is evident just behind the gill plate while the second "stripe" is best described as a darkened area at the base of the tail. They are found throughout the Eastern Indian Ocean and Western Pacific, usually in association with branching corals such as Pocillopora eydouxi.

Dascyllus strasburgi:
I have never yet seen this species for sale. They are native to the Marquesas Islands where they can be found associated with Cryptodendron species anemones. They are a medium-sized Dascyllus, typically reaching three and a half inches in length.

Dascyllus trimaculatus:
This species is the other extraordinarily common humbug species, the Domino or Three-Spot damsel (photo right). They are also the largest of the Dascyllus species, even though the FishBase website lists them as reaching only a little over four inches in length. I have seen them myself easily approaching a bruising six inches long! That makes this deep-bodied fish about as large as a coffee saucer and rather intimidating when full grown. They are found inhabiting both anemones and coral heads, as well as the occasional biker bar looking to pick a fight. Their coloration can vary by geographic location, ranging from the common all black with three white spots to black with white spots and a yellow belly to an almost all black variety, although these color variations do not denote separate species.

Finding a healthy specimen in this genus is usually quite easy. I generally avoid any newly arrived acquisition, preferring to wait until it has been in the dealer's tank for at least a few days to a week. This is especially important when dealing with damsels. They are cheap and, unfortunately, are treated as such. Typically, they are shipped in small bags with very little water to save on freight charges. That means they are prone to suffer from Post Traumatic Shipping Disorder, a term Morgan Lidster coined to cover the broad number of reasons that an animal could die shortly after shipping but of no apparent direct cause (i.e., parasitic, bacterial, etc.) such as temperature extremes, low dissolved oxygen, depressed pH and so on. Generally, once they have remained in a dealer's tank for three days to a week or more, I would consider them safe enough to purchase. I would, however, still suggest that these fish, like any other addition to the display, undergo a proper quarantine period so that they are screened for disease, permitted time to adjust to prepared foods and gain some weight before being thrust into the competitive environment of the display.

Also, I do not suggest buying those tiny, cute little ones that are occasionally offered for sale. Many times I have seen damsels that are about as big around as a dime, sometimes even smaller, and I avoid these specimens like the plague. As with many fish species, the smallest and the largest individuals should be avoided (Fenner, 2001). In my experience, the largest adults often refuse to eat prepared foods. I believe they have simply been in the wild for too long to adjust to life in captivity. On the other hand, the babies that come through the chain of custody have a high mortality rate, too. It is my opinion that these are half starved by the time they get to the local dealer's tanks where they may receive routine feedings. Also, they don't tolerate shipping nearly as well as slightly larger specimens.

Finally, I avoid specimens from a tank containing other dead or dying fish. Whether the deaths can be attributed to shipping problems, aggression, disease, etc. makes little difference. All are signs that aquarists should avoid specimens from that shipment or that dealer for the time being.

Damsels, in general, and Dascyllus species, in particular, are relatively forgiving aquarium residents. They are not especially demanding of water quality. Many times, these fishes are used to cycle aquariums (a practice which I do not encourage), and consequently they are exposed to high levels of ammonia and nitrite and generally subjected to less than ideal conditions. But, many times they survive and thrive nonetheless. It is a testament to their hardiness and resiliency that they can be abused in such a manner and still live. But as standard practice for a conscientious aquarist, we should all remember that we are talking about live animals and should strive to provide them with the best environment possible.

They should be given plenty of cover so that they may setup territories to defend. Ideally, they would have a natural "host" to associate with, or at the very least, a reasonable approximation. And, while most stores keep their tanks crowded in an effort to minimize aggression, this is only a short-term solution. For long-term, regular care, they should be given plenty of room and overcrowding should be avoided. Furthermore, be prepared to thin out the group. Usually a dominant individual or pair develops if a small group is purchased and introduced at the same time. This lone alpha or top pair then typically goes on a rampage, aggressively harassing all others of the same species. That is simply the price to pay for keeping these fishes, so plans should be made accordingly.

In general, damsels readily accept a variety of foods, and Dascyllus species are no different. They are naturally zooplankton eaters and as such should be offered similar substitutes such as Mysis shrimp, Pacifica plankton, bloodworms, Cyclop-eeze™, and SweetWater™ Zooplankton (Daphnia). I prefer to use frozen (and of course, thawed) or refrigerated versions of the previous examples over the freeze-dried offerings. I also routinely soak the foods in vitamin and lipid supplements such as Boyd's Vita-Chem and American Marine's Selcon^®. It is also advisable to introduce some vegetable matter into their diet. These fishes are substrate spawners (Fenner's website) and are known for cleaning and eating various algae from where they intend to lay their eggs. Introducing nori and similar commercial algal preparations would be a good idea for varying their diet. But, in reality, getting these fishes to begin eating is rarely an issue. Of more pressing concern is making sure their tankmates get something to eat when housed with these voracious feeders.

As I already mentioned, these damsels are fiercely territorial. Care should be taken in selecting appropriate tankmates for these fish. While they should be housed with other fish that are equally as scrappy, remember that to many marine predators, damsels are the aquatic version of "popcorn" (Fenner, 2001). Many are bite-sized tasty morsels that can easily be gulped down by groupers, lionfish, eels and other predators.

Compatibility chart for Dascyllus species:

Fish	Will Co-Exist	May Co-Exist	Will Not Co-Exist	Notes
Angels, Dwarf	X			Should co-exist well.
Angels, Large	X			Should co-exist well.
Anthias			X	Will likely be harassed and/or killed by the damsel.
Assessors			X	Will likely be harassed and/or killed by the damsel.
Basses		X		Will be susceptible to damselfish attacks.
Batfish		X		Damsels may harass batfish, attacking their excess finnage.
Blennies	X			Should co-exist well.
Boxfishes		X		Slow and unable to get out of the way, boxfishes are likely to be excessively harassed.
Butterflies	X			Should co-exist well.
Cardinals			X	Will likely be harassed and/or killed by the damsel.
Catfish	X			Should co-exist well.
Comet		X		Comet will likely stay hidden more than usual.
Cowfish			X	Will likely be harassed and/or killed by the damsel.
Damsels		X		Not recommended unless paired individuals are obtained.
Dottybacks		X		While likely battle to a stand-off if the sizes are similar.
Dragonets		X		Ignored on most occasions.
Drums			X	Will likely be harassed and/or killed by the damsel.
Eels	X			Should co-exist well.
Filefish		X		Likely to be harassed, especially Chaetoderma pencilligera.
Frogfish			X	May attempt to consume the damsel.
Goatfish			X	Will likely be harassed and/or killed by the damsel.
Gobies			X	Varies greatly between species, but the majority will be harassed.
Grammas		X		Will likely find a quiet corner and never move from it when housed with damsels.
Groupers		X		Will co-exist until they are large enough to swallow the damselfish.
Hamlets			X	Will be susceptible to damselfish attacks.
Hawkfish	X			Should co-exist well.
Jawfish		X		Not recommended, but once established a jawfish can hide in its burrow and escape damselfish attacks. May remain mostly hidden in the presence of the more aggressive damsels.
Lionfish			X	May attempt to consume the damsel.
Parrotfish	X			Should co-exist well.
Pineapple Fish	X			Should co-exist well.
Pipefish			X	Will likely be harassed and/or killed by the damsel.
Puffers		X		Another slow mover that may be the object of frequent, repeated attacks.
Rabbitfish	X			Should co-exist well.
Sand Perches		X		Aggressive enough to hold its own, but the sand perch may consume smaller damsels.
Scorpionfish			X	May attempt to consume the damsel.
Seahorses			X	Will likely be harassed and/or killed by the damsel.
Snappers			X	May attempt to consume the damsel.
Soapfishes		X		Large individuals may attempt to consume damselfish.
Soldierfish	X			Should co-exist well.
Spinecheeks			X	Will hide continually in the presence of an aggressive fish.
Squirrelfish	X			Should co-exist well.
Surgeonfish	X			Should co-exist well.
Sweetlips			X	May attempt to consume the damsel.
Tilefish			X	Tilefish do not mix well with aggressive fish.
Toadfish			X	May attempt to consume the damsel.
Triggerfish	X			Should co-exist well except with the most aggressive of triggers.
Waspfish	X			Should co-exist well assuming the waspfish is unable to swallow damsel.
Wrasses		X		Should co-exist well except for the small docile wrasses.

Note: While many of the fish listed are good tankmates for Dascyllus species, you should research each fish individually before adding it to your aquarium. Some of the mentioned fish are better left in the ocean or for advanced aquarists.

In addition to conflicts with other fishes, be prepared for your Dascyllus to occasionally bite you. Not only is this not unheard of, it actually is quite common, for Dascyllus damsels to bite their owners while the aquarist's hand is in the display doing normal tank maintenance such as placing a new coral, rearranging the rockwork or simply cleaning the viewing panes. Again, it is simply the price of keeping these fishes.

Yet, with all generalizations, there are exceptions to the rule. For instance, the Cloudy/Blue-Spot and Reticulated/Two-Stripe humbugs are not as aggressive as the rest in this genus. But, they are also are not as attractive, as readily available or as hardy as the others, either.

As a general rule, Dascyllus are not known for being plagued by many diseases. They, of course, can be infested with all the standard diseases such as Cryptocaryon and Amyloodinium, but not more so than many other fishes. A simple quarantine period to screen for potential pathogens is all that is required here. And, if a disease is detected, they respond well to just about any treatment protocol: hyposalinity, copper, freshwater dips and formalin baths (Fenner's website).

As further proof of their hardiness, Dascyllus damsels have been reported to live over ten years in captivity (Fenner's website). All that is necessary is to select a reasonably healthy specimen, screen it for disease, and provide a proper environment, and aquarists will be rewarded with an aquatic pet for many years to come, that cost only a few dollars to purchase.

I mentioned in the species breakdowns that these fishes are usually found in close association with various cnidarians. This should be no surprise to anyone who recognizes that these fishes are closely related to clownfishes. Studies have even shown that this relationship is beneficial to both animals (Liberman, Genin, & Loya, 1995). The fishes obviously get a place to hide to avoid predation, while the corals have been shown to have increased growth rates as compared to other corals grown without the humbugs. It was hypothesized that the fishes provided nutrients from their waste material that fueled the corals' growth. They also provide some extra water movement in and among the dense coral branches that they dwell in during the night, increasing dissolved oxygen content and again spurring increased growth (Goldshmid, Holzman, Weihs, & Genin, 2004).

These boisterous fishes are definitely not for everyone or every display, but their bold color patterns, hardiness and relatively inexpensive purchase price do make them an attractive choice. All that's needed is to plan accordingly for their special needs. And, their bite is really not that bad. It scares more than it actually harms you the first time it happens. After that, you either get used to it or get some gloves.