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Even the most unfamiliar person recognizes "Nemo" and other Clownfishes as such on encountering them in aquariums or underwater on tropical reefs. Similarly, their closely related cousins, the often-feisty Damselfishes are easily noted as marines. Though they comprise a large (some 350 described species and counting) assemblage of mostly smallish fishes, only a few are good choices for small/er system stocking. Most are too agonistic/aggressive to fit in with other fish and some non-fish tankmates; several only live well and long in a shoaling situation, requiring a larger volume/world. Others either grow too large or just can't handle the stress of small confines. Thankfully, there are a few genera of damsels and a couple clown species that do quite well in "Nano" size systems. These and their basic husbandry is the subject of this article.
The family Pomacentridae, Damselfishes, (subfamily Chrominae) and the Clownfishes (subfamily Amphiprionae) are important reef fishes on a few counts. They are found everywhere on tropical shallow water environs where there is sufficient cover and forage, providing micro-algal cleaning (even culture in some cases) services, functioning as food items for larger predators, and act significantly in determining the livestock make-up of their well-defined lek & feeding territories.
For us as marine aquarists, several of the Pomacentrids factor as key captive choices, for their hardiness, beauty, and interesting behaviours. Of the dozen or so commonly kept species, all are generally "reef safe", tolerant of wide/r and varying chemical and physical water quality, typically disease-resistant, and accepting of all types of prepared commercial foods.
Best Species for Small System Use:
Genus Acanthochromis: Monotypic/one species.
Genus Pomacentrus: The fifty six described species of this Damsel genus contain many peaceful aquarium possibilities. I list a few of the more commonly available here.
Clownfishes: Ocellaris and Perculas. Tank-bred and reared specimens are FAR superior to wild-collected. If keeping two individuals, start them small and keep your eyes open for too-severe territoriality over time. You and they don't need, or likely want an anemone. Other writers endorse the use of other tank bred species in small volumes (e.g. Clark's, Tomatos); but I have found these rarely work out in time.
Do take heed of the species and genera identified above as appropriate and avoid others of the family. Other Damsel genera get too big, are too pugnacious, or just can't adapt to small volumes for whatever reason/s. Other Clownfish species are inappropriate for "Nanos" even if bred/reared in captivity, grow too large and mean for use in small systems.
In terms of picking out individual specimens, look for smallish, outgoing ones in good shape. In particular, select against broken fins, missing scales or otherwise blemished specimens. Don't buy just arrived fishes, instead choosing amongst ones that have been on hand for at least a few days.
For smaller systems'¦ twenty or so gallons, one specimen, solo is recommended'¦ for larger 30-40 gallon ones, with considerable dÃ©cor/visual cover, two specimens may learn to get along.
Similar appearing fishes are often harassed, to the point of death at times. Many small bottom dwellers such as Blennioids and Gobioids are left alone; are not evidently perceived as competitors for space and food. As the Pomacentrid/s is likely to be the more/most aggressive species in your system, you should plan on adding it/them last.
Surface area is far more important to these fishes than open/top swimming space. Though there are some other species of Pomacentrids that spend a good deal of their time out and off the bottom, the ones that are suitable for small systems live the majority of their time, in and amongst hard structure (rock, corals'¦) scattered about the bottom. Best for you to arrange decorative elements spaced accordingly so your Damsel/s or Clown/s can dart in and out amongst such structure.
As previously stated, these fishes are notably not particular re what sorts of foods they consume. You will notice that they spend a good deal of the daylight period looking about and picking at algae et al. Better that their systems are not kept scrupulously clean of growing foods, and that some small amount of food be added at least twice a day in addition.
Most all Damsels are wild-collected and do occasionally "come in" with the usual reef fish diseases (Cryptocaryon, Amyloodinium)'¦ Additionally, other external and internal parasites are encountered at times. Wild-collected Clownfishes are notorious for such dire problems, many succumbing to Brooklynellosis'¦ hence the strong suggestion to buy captive-produced specimens.
One can preventatively treat these fishes'¦ with Quinine Compounds for external Protozoan parasites, Anthelminthics for internal and external worms of all sorts, and anti-protozoal added to foods to discount gut parasites. Generally these regimens are of more harm than good, and considering the low stocking levels of small marine systems, I am more inclined to simply select apparently healthy individuals, and isolate/quarantine them a few weeks ahead of permanent placement.
The majority of Damselfish (including Clownfish) species in the world are unsuitable for small aquarium use; for reasons of temperament, size, and/or psychology. However, there are a select number that live in small "patch" areas in the wild, and do just fine in small systems. The requisite considerations for success with these include selecting the right species, good specimens, and late placement in suitably (densely) decorated settings.
Albeit feisty, Pomacentrids are mostly hardy, interesting and forgiving marine aquarium species.
Allen, Gerald R. 1975. Damselfishes of the South Seas. TFH Publications, Neptune City, N.J.
Allen, Gerald R. 1979. The Anemonefishes of the World: Species, Care & Breeding; Handbook for Aquarists, Divers and Scientists. Aquarium Systems, Mentor Ohio.
Allen, Gerald R. 1991. Damselfishes of the World. Aquarium Systems, Mentor, Ohio.
Axelrod, H.R. & Warren E. Burgess. 1981. Damselfishes and Anemonefishes. TFH 9/81.
Baensch, Hans & Helmut Debelius. 1994. Marine Atlas, v.1. MERGUS, Germany. 1215pp.
Emmens, C.W. 1984. Damselfishes. TFH 9/84.
Fenner, Bob. 1989. Successfully selling the popular marines. Pets Supplies Marketing 1/89.
Fenner, Bob & Cindi Camp, 1991. Damselfishes, saltwater bread and butter. FAMA 10/91.
Fenner, Robert. 1998. The Conscientious Marine Aquarist. Microcosm, VT. 432pp.
Fenner, Robert. 1999. The indomitable damsels- Family Pomacentridae. TFH 1/99.
Flood, A. Colin. 1992. Those darling damsels. TFH 8/92.
Wilkerson, Joyce D. 1997 Clownfish; a guide to their captive care, breeding & natural history. Microcosm, VT. 216 pp.
A peaceful damsel for a nano.../Damsel Compatibility