Ask the WWM Crew
|Please visit our Sponsors|
Damselfishes are an extremely important group of ubiquitous, circumtropical coral reef fishes. Along with the clown-anemone fishes (Amphiprion, Premnas) Damselfishes make up the family Pomacentridae, with some 25 genera and about 333 species. Anemonefishes (sub-family Amphiprionae) are covered elsewhere (see link above).
Damselfishes provide a vital link both as reef forage fishes as well as excellent beginner marine aquarium specimens. Their extensive use is well-warranted considering their diversity, beauty and tolerance of chemical and physical conditions, gregariousness when crowded and general compatibility with fishes and invertebrates. Most damselfish species accept all types of food eagerly and are very disease resistant.
Damselfishes are generally small with some species, like the California garibaldi (Hypsypops rubicunda) and the giant Cortez damsel (Microspathodon dorsalis) reaching one foot in length. Many are brilliantly hued in blues, greens, violets, reds and browns; several appear metallic. Quite a few are or become drab brown or olive later in life and there are sometimes striking color and structural differences between the sexes.
The family's taxonomy in currently poorly known and a wide open field with species "groups" blending/grading between island groups. On the higher taxonomic plane, Pomacentrids are closely related to cichlids which they resemble in structure, form and behavior. Both families are in the same sub-order of the largest order of fishes, the Perciformes. These two families are notable within the group for being the only two with one pair of nostrils (nares). Most damsels reproduce like many substrate spawners; their behavior is similar to typical central-American neo-tropical cichlids. Other similarities include an incomplete lateral line, toothless palate, single, continuous dorsal fin and territorial behavior.
On any given day a handful or two of species are readily available from dealers. This mix generally includes three-spots or dominoes (Dascyllus trimaculatus, three and four stripes or humbugs (Dascyllus aruanus et al.) yellow-tail blue and blue damsels (Chromis cyaneus et al.) various Chromis, beaugregorys, sergeant majors (Abudefduf species), so-called "deep water" damsels (Glyphidodontops species et al) among others.
As with many cichlid species, the following generalities exist when picking out damsels:
1) Buy from reputable dealers; ones who earn your trust, that feed, care for their stock and your business.
2) Buy from systems with no dead or dying specimens. Look for signs of gill burn/ammonia poisoning from recent shipping; cut-marks from mis-handling or aggression and avoid that tank. Beware tanks of damsels with individuals hanging around or drifting around having "private meetings".
3) Don't buy the smallest (<3/4 inch) or the largest individuals available. Small ones may die easily and large ones usually don't adapt well to captive conditions.
4) Buy them all about the same size; this reduces inter and intra-species aggression and alleviates some "picking-out" by the customer.
5) Buy stock that have acclimated-stabilized. Damsels that have been adequately acclimated and held for just a day or two are usually extremely hardy.
Damselfishes are easy to keep in aquaria; they are not fussy in terms of water chemistry and physics.
Use one or more aquaria of twenty to sixty gallons; the smallest practical maintenance & display size to the largest practical netting size. Temperatures in the low to upper 70's degree F. (72-78). Most tolerate and enjoy a wide range of salinities. We keep ours in a specific gravity of @ 1.017-1.018 to decrease salt mix costs, increase gas solubility, reduce algae growth and curtail epizootic outbreaks.
Any amount of light, dim to bright, seems OK. Water quality likewise, is generally not critical; most are collected in polluted waters! Natural or synthetic water makes no difference in terms of vitality or reproduction in captivity. A pH of 7.5 to 8.3 is favored; no ammonia, nitrite and as low a concentration of nitrates as practical is the rule as with most marines.
Many people take the risk of introducing pests, parasites & pollution by using a "floating & mixing" technique, then pouring the damsels into their system. Don't do it! At the very least, appropriate procedure should involve bringing temperatures about equal, a freshwater dip with or without formaldehyde &/or copper (see our article on Acclimation...) & if possible, a two week quarantine.
Damselfishes are a group that are better to start feeding as soon as possible. Frequent, small feedings of a variety of foods (dry, frozen, fresh, & live; both vegetable and animal) will help settle in the stock and reduce aggressive turmoil.
1) Territoriality may be alleviated by either over-crowding them 2-3 or more per gallon or way under-crowding, one or less per 5-10 gallons.
2) If possible, buy a batch and introduce them to a new damsel-free tank all at once. If not possible/practical to do, move the tank decorations around, upsetting territories, when introducing new specimens.
3) They like hiding spaces. Provide coral, shells, plants- some nooks and crannies for social-psychological shelter. Keep the number and type of decorations simple to facilitate removal for netting out damsels.
4) Some damsels, especially when they get larger and more aggressive, should be displayed with no other damsels. Examples include neon-velvets, dominos, Hawaiian Dascyllus, giant sea of Cortez and garibaldis. Keep your eye on your populations and move those bullies. These may be maintained with angels, tangs, most triggerfishes, etc.
5) Be aware that small damsels are a dietary mainstay for most fishes whose mouths are large enough to accommodate them. Measure those Lionfishes and basses before introduction.
Some Damsels are specialized planktivores to herbivores in the wild. In captivity damsels accept all foods greedily. In fact, sergeant-majors are legend for their use in training other shy species to surface feed.
Frequent small feedings 2-3 times per day of a mix of foods sustain them well. Nutritional diseases are all but unknown in this family.
Infectious and Parasitic Disease:
Damselfishes are parasitized internally and externally by several species of sporozoans, Cryptocaryon, Amyloodinium, roundworms, flukes, tapeworms and crustaceans. The presence, abundance and susceptibility of these parasites to varying salinities and treatments is complex. Damsels for the most part are disease resistant and if preventative measures have been executed and their environment is optimized you can expect low parasite loads.
Most treatable conditions (external) can be excluded by the freshwater dip treatment and low specific gravity mentioned before. Damselfishes respond well to periodic prophylactic copper treatments. Internal "worm" parasites are sometimes easy to diagnose but difficult to cure. For internal problems, most preventative and treatment therapeutics applied via food, injection or bath for internal parasite control should be avoided as they will probably do more harm than good.
It should be mentioned in passing here that every now and then a sort of wipe out syndrome occurs with a given tank of damsels. What the causative factor(s) are is not clear. If you experience a sudden large die-off, it is best to immediately remove, dip and place the remaining live damsels in a new tank and dump, and bleach, acid wash or throw away the substrate from their old tank. This wipe-out syndrome may occur even in aquaria on a centralized filter system. Watch your fish!
can be a type of social disease. Keep your stock over or under-crowded, observe for extreme interactions and remove all bullies. Inter-specific aggression is probably the single largest source of damselfish mortality.
How long do they live? Some damsels have been kept in captivity for more than ten years and known to have lived more than twenty in the ocean.
Major areas of interesting damselfish biology will not be explored here. Chemical and sound communication, breeding and other behavior are rich adventures to be explored in a literature search and in your own tanks.
Allen, Gerald R. 1975. Damselfishes of the South Seas. T.F.H., Neptune City, N.J.
American Society of Ichthyologists and Herpetologists, 1978. The Biology of the Damselfishes a symposium held during the 56th annual meeting of the ASIH. Rosentiel School of Mar. & Atm. Sci. U. of Miami, 1980, 145-328
Bunn, D., 1987. Spawning the Dusky Damsel. Aquarist Pondkpr. 52(1):41
Gronell, A.M., 1984. Look-alike Damsels. Tropical Fish Hobbyist Magazine 32(8) 48-53
Hemdal, J., 1985. Pomacentrids of the Atlantic. Freshwater and Marine Aquarium Magazine 8(4) 48-52