Ask the WWM Crew
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Guess how many Cardinalfish species are described by science… one hundred? Two? According to Fishbase (.org), there are currently some three hundred forty five arrayed in thirty two genera. Though this useful database states that they (sic) “do generally well in aquariums”; some are too large (a few up to 8 in., 20 cm.) or too aggressive to be kept other than solitarily in small volumes. This last includes the most popular, commonly offered species in the trade, the Pajama and Banggais. Most live well enough in groups of solitarily; getting along with other fishes and invertebrates that get along with them.
As you’ll see here, there are several other suitable, more punctuated offerings that do better in systems of tens of gallons. We’ll do the usual brief run-down on the whole family, list the better choices, and proffer some notes on how to pick out healthy specimens.
Many Cardinalfishes, family Apogonidae ("App-oh-gahn-id-ee") are reddish in color (hence their common name) mixed with silver and white, though most species are yellow, silvery and black. All have large eyes, and are largely nocturnal; hiding in crevices or beneath ledges by day (typically with Squirrelfishes, Bigeyes and sweepers). These are mostly shallow water fishes, found from the surface to about 100 meters. Some species are found (and should be kept) solitarily; others are definitely schoolers and do far better kept in small groups. We’ll discern twixt as well as mention where species have in recent times been split off into new genera; you will likely find them on the Net, in older references listed under the olde.
Species of Interest/Use to Aquarists:
Genus Archamia: Not often seen in the trade
Genus Sphaeremia: Py/ajamafishes.
Cardinals display little middle-ground in their quality on-arrival; they are either hardy and sure to "make it", or thrashed and "doomed" to break down and die. For reference, they share many of the same selection criteria as damselfishes.
1) Behaviorally; look closely at the individuals on display. Schooling ones should be clustered somewhat, with none having "private parties" off in the corners of the system. Are they aware of your presence? Watching your movements? Good.
2) Cut marks and reddening: Examine the bodies of each specimen carefully, especially the insertions of unpaired fins. Do you see evidence of infection on any individual? If so, pass them by.
3) Feeding… the all-time best “acid test”. Always ask that prospective purchases be fed the sorts of foods you’ll employ… in front of you.
4) How long have the fish been on hand? Don’t buy just arrived specimens. The ones that are doomed will perish within a few days of arrival. This being stated, don’t leave them too long at your dealers as they often are starved in the process of collection, holding, shipping… and too thin specimens perish easily.
5) Size matters. Most too-small cardinals don’t make it. Banggai’s
are the best example here. None should be moved till they are at least
three quarters inch total length. You want to buy juveniles, but not
ones that are much younger than sub-adult.
I'd like to mention that Apogonids are an under-rated portion of the living reef's populations. Several of the hundreds of species are of large number in the wild, just not commonly encountered due to their largely nocturnal habits. Many form close associations with invertebrates, living within the spiny shelter of urchins, sea stars and more.
For a really outstanding arrangement, provide a large dark shelter-space with one opening and a group of these fishes and others they are found with in the wild. The under ledge and cover sub-habitat is a rich biotope in the reef world.
Most Cardinalfishes as individuals get along with their own kind, other species of Apogonids and other peaceful tankmates. As noted a few times above; there are species that as adults (breeding size) can, do bicker with their own kind.
Smaller species are strongly promoted for use in fish-only and reef-tank set-ups of only tens of gallons. They are supreme choices, being hardy and interesting; their only shortcomings being that they're shy and reclusive. Apogonids as a rule do not "sample" more than mouth-size invertebrates.
Reproduction, Sexual Differentiation/Growing Your Own:
As you’ve seen, some Cardinals are far more suitable for small aquarium use than others. My advice is to wait a few months after setting up your new system, to allow it to become stable, give time for live rock organisms to get situated, inoculate the sand bed; add what invertebrates you intend to stock, and then introduce your Cardinals as first fish.
Allen, G.R & Donaldson, T.J. 2007. Pterapogon kauderni. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2 http://www.iucnredlist.org/apps/redlist/details/63572/0, Environ. Biol. Fish. 57:142.
Dodds, Kieron. 2009. Cardinal Sin: The Plight of the Banggai Cardinalfish Pterapogon kauderni KOUMANS 1933. TFH 1/99. http://www.tfhdigital.com/tfh/200901/#pg95
Hopkins, Steve & Harry Ako and Clyde S. Tamaru. 2005. Manual for the Production of the Banggai Cardinalfish, Pterapogon kaudnerni, in Hawai‘i www.raingarden.us/banggaimanual.pdf
Lunn, K.E. and M.-A. Moreau. 2004. Unmonitored trade in marine ornamental fishes: the case of Indonesia’s Banggai cardinalfish (Pterapogon kauderni). Coral Reefs. 23:344-351.
Marini, F. 1998. Frequently Asked Questions and Answers on Banggai Cardinals. Reef. Org archives. http://www.reefs.org/library/article/f_marini.html.
Marini, F. 1999. Captive care and breeding of the banggai cardinal fish "Pterapogon kaudneri". http://www.reefs.org/library/talklog/f_marini_020799.html
Michael, S. 1996. The Banggai Cardinalfish: A newly available species that may become to popular for its own good. Aquarium Fish Magazine. 8(8):86-87.
Tullock, J. 1999. Banggai cardinalfish alert. Aquarium Frontiers. http://www.aquariumfrontiers.net/EnvironmentalAquarist//html.
Vagelli, A.A. 1999. The reproductive biology and early ontogeny of the mouthbrooding Banggaai cardinalfish, Petrapogon kauderni (Perciformes, Apogonidae). Environmental Biology of Fishes. 56:79-92.
Vagelli, A.A. 2004. Significant increase in survival of captive-bred juvenile Banggai cardinalfish Pterapogon kaudneri with an essential fatty acid-enriched diet. J. World Aqua. Soc. 35(1):61-69.
Vagelli, A.A. and M.V. Erdmann. 2002. First comprehensive ecological survey of the Banggai cardinalfish, Pterapogon kaudneri. Environ. Biol. Fish. 63:1-8.
Vagelli, A.A. and A. V. Volpedo.
2004. Reproductive ecology of Pterapogon kaudneri, an endemic
apogonid from Indonesia with direct development. Environ. Biol. Fish.