Favia fragum FAVFRA-121597-TOOROB-001

This entry was posted on Monday, December 15th, 1997 and is filed under Corals, Spawning Reports.

The Breeder’s Registry© Information contained in this report is taken from submitted observations from aquarist unless noted otherwise (see comments). Information may be reproduced providing the Breeder’s Registry is cited.

Breeder ID: FAVFRA-121597-TOOROB-001

Date received: 12/15/97

Identification: Favia fragum (Esper, 1795)

Geographic origin: Caribbean, U.S. Virgin Islands  

Taxonomy: (after I.C.Z.N.)

Kingdom Animalia

Phylum Cnidaria

Class Anthozoa (Ehrenberg, 1834) Subclass Zoantharia

Order Scleractinia (Bourne, 1900)

Family Faviidae (Gregory, 1900)

Genus Favia (Oken, 1815)

Species fragum (Esper, 1795)

Description: Massive; plocoid, intramural budding; defined costae but not thickened near the wall, slightly rough to the touch; spongy columella; septothecal wall.

Colony Form / Shape: plocoid / massive; size generally <30 cm in diameter. Not considered importantant in western Atlantic reef building (Wood, 1983)

Budding: intramural,

Columella: trabecular and continuous,

Corallite Size: medium (typically 1.5 – 10mm), generally nocturnal

Wall Structure: septothecal or parathecal,

Lobes: none.

Coloration: yellow to brownish

Environmental: generally found in shallow waters on rocks or rubble

Extant species:

F. dominicensis (Vaughan in Vaughan & Hoffmeister,1925)

F. fragum (Esper, 1795), Caribbean

F. gravida (Verrill, 1868), Brazilian waters

F. leptophylla (Verrill, 1868), Brazilian waters

(Australian species)

F. favus (Forskal, 1775)

F. helianthoides (Wells, 1954)

F. laxa (Klunzinger, 1879)

F. lizardensis (Veron, Pichon & Wijsman-Best, 1977)

F. maritima (Nemenzo, 1971)

F. matthaii (Vaughan, 1918)

F. maxima (Veron, Pichon & Wijsman-Best, 1977)

F. pallida (Dana, 1846)

F. rotumana (Gardiner, 1899)

F. rotundata (Veron, Pichon & Wijsman-Best, 1977)

F. speciosa (Dana, 1846)

F. stelligera (Dana, 1846)

F. veroni (Moll & Borel-Best, 1984)


How long have you maintained organism(s): 5 mo, 17 mo.

Size: One head is ~25 mm (~1″) in diameter, the other is ~66 mm (~2.6″)

Sex: Simultaneously hermaphroditic (possibility of selfing unknown)

Diet: Newly-hatched Artemia nauplii (un-supplemented), 1-4 times / week (depending on my schedule — I try for every second day, but often end up feeding only once a week or so when I get busy)


Describe any preparation(s) or pre-spawning activities: Nothing special — the coral was simply removed from the aquarium and isolated into a 2 L beaker for observation around the full moon (these corals spawn naturally on a lunar cycle with a 2.5″ head releasing, on average, about 100 larvae in the wild – D. Carlon, pers. comm.).

Time of spawning: Overnight during the 4 days preceeding the full moon (Dec ’97).

Frequency of spawning: Presumably monthly, although this is the first time that I have checked for larval release in the aquarium. Many corals undergo natural cycles of gametogenesis in the wild, and release or resorb larvae between reproductive peaks which coincide with the full moon (examination of F. fragum in the field shows distinct cycles of gamete production: reproduction peaks near the full moon and reaches its minimum near the new moon – D. Carlon, pers. comm.).

Location of spawning: 2 L glass beaker placed beside the aquarium.

Description of Spawn: About a 6-20 coral planulae were released during each of four consecutive nights from the large head and most looked like a “typical” cnidarian larva: a semi-cylindrical blob, covered with cilia for locomotion and lacking any obvious sensory structures or cephalization. The small head released only a few larvae (3-5) on each of the 2 “middle” nights of the 4 day spawning event. A couple of the released larvae were obviously deformed and appeared unable to swim directionally, but these were the exception, and most larvae appeared fine. A couple of the “normal” larvae were examined under a dissecting microscope. They appear normal and healthy, and each contained a significant number of zooxanthellae, presumably derived from the parent colony. The number of zooxanthellae in the larvae were remarkable, and the surface of the larva was highly speckled due to the presence of the algae — I would estimate that about 1/4 of the surface of the larvae appeared dark (under high magnification) from inclusion of algal cells. The larvae were active swimmers, but spent most of their time bouncing along the bottom, apparently in search of some indication of habitat suitability for settlement.

Size: Variable depending on activity — the larva become elongate when swimming, and almost spherical when examining a substratum. In general the larvae were ~0.5-0.8 mm

Additional Notes: There have been many reports of metamorphic inducers isolated from coralline algae (from the lab of Dan Morse and colleagues), but the validity of these results has been questioned by other marine biologists (e.g., Fu-Shiang Chia, Joe Pawlik) working on metamorphic inducers. An uncontested, substratum-derived metamorphic inducer has yet to be identified for any invertebrate larva. In my personal experience, placing a small rock covered with coralline alga (from my reef tank) into the observation bowl behind my tank seemed to have no effect on the larvae isolated in it — the sole larva that settled did so on the bottom of the glass bowl rather than on the coralline-coated coral rubble.

Size of eggs/fragment: ~0.5-0.8 mm (see above)

Approximate quantity: ~50 total, ~20 individual planulae peak release on any given night.

Were planulae removed to a separate tank? Coral spawned in isolation container (see above), and planulae were then removed from that container to either 4″ diameter glass observation dishes maintained in the sump, or to 15 ml plastic vials floated in the aquarium.

If so, how? Larvae were individually collected with a Pasteur pipette

Describe development of eggs/planulae: N/A — internally brooding species.

Incubation period: Unknown length of time as brooded larvae in the adult, but unlikely to exceed a few weeks; corals examined in the field have few planulae during the new moon, but release on the order of 100 during the full moon. Larvae are released fully developed and are supposed to be competent to settle within hours, if not immediately (D. Carlon, pers. comm.). Behavioral observations on aquarium-raised larvae, are consistent with expectations from the field.

Time of hatching: Larvae are brooded internally, and released fully developed.

Larvae attracted to light? No, although larvae are supposed to be phototactic immediately upon release, they become photo-negative within hours and avoid light by the next morning (D. Carlon, pers. comm.). This is presumably a response to being released on the full moon — larvae swim towards the light for a short period of time to enhance dispersal by ocean currents, but then begin to shun light and search for a site for attachment before dawn (when they would be highly obvious to visual predators). I did not observe the behavior of larvae immediately following their release, so I cannot comment on early phototaxis. By the following morning, however, larvae swam away from any areas of bright lighting.

Additional comments: Captive larvae did not settle the first night (as would be predicted based on field observations), but did settle and metamorphose the second night if kept in clear plastic containers within the reef tank itself. Larvae moved to a separate container outside the reef tank (but using water from the main aquarium at the same conditions, minus the lighting) continued to swim for a week (and still counting) without settling. Of the 6 larvae isolated in a separate observation container, only one settled (after 3 days), while 3 eventually died and the other 2 failed to metamorphose within the week (and are still swimming around the bowl). The single larva that did settle and attach to the bowl is developing very slowly, and may not survive. Of the larvae kept in the aquarium during the same period only 2 died, while the remainder settled the night after being released. In-tank settlers appear to be developing normally; the settled larvae have divided into the septa of the first polyp, and appear to be growing well. I am not feeding these juveniles, but they appear to be gaining enough nutrition from the light (as I mentioned above, the larvae are FULL of zooxanthellae) and possibly from capturing picoplankton in the aquarium.


Capacity (Gallons): 43 gallons

Dimensions: 48″x13″x16″ (LxWxH)

Are sides or back covered? No (although the back wall is coated in coralline growth and could be considered “covered”)

Filtration: Skilter® 400

Pumping volume: 60 gph.

Type of seawater used: Instant Ocean® or natural, depending on availability.

Frequency/Volume of changes: Irregular (when necessary) 50-100% water changes, depending on tank conditions.


Specific Gravity: 33-35 ppt

How measured? Refractometer

Source of replacement water: Instant Ocean® mixed with distilled water when necessary, 1 micron filtered natural seawater when possible.

pH: 8.2-8.4, depending on time of day measured, 8.3 average.

How measured? SeaTesT® (Aquarium Systems) pH test kit

Temperature: annual: 78-84 F , currently 80-84 F

Fluctuation: ~4 degrees daily, but shifting towards ~78-82 F in summer (we have strong A/C), and about ~80-84 F in winter (due to building heating).

Nitrates: currently <0.2 mg/L

How measured? SeaTesT® (Aquarium Systems) low range nitrate test kit

Calcium: 450-500 ppm, currently 480 ppm.

How measured: SeaTesT® (Aquarium Systems) calcium test kit

Other parameters not listed: currently <0.2 mg/L PO4

Additives, medications added: KI, CaOH

Frequency and dose: I add a few drops of saturated KI when I remember: all evaporation is replaced with saturated kalkwasser a couple of times a week on a slow drip overnight.


Lighting : 4x40W (160W total) NO flourescent lights (2 Coralife Trichromatic®, 1 Phillips® Actinic/03, 1 Hagen PowerGlo®).

Photoperiod: From when the first person arrives in our lab in the morning (usually about 6:00 AM) and turns on the lights until the last person leaves at night (completely unpredictable) and turns the lights off. All 4 bulbs are on a single switch, and we don’t use any timers or graded
lighting — the lights are either on or off with the room light switch. The lights are often left on for days on end, and may be left off for days on end as well (particularly on the weekends). There is no natural light hitting the aquarium at anytime, and no moonlighting or any other
supplemental lighting is provided.

Average distance from surface: ~2″ (the bulbs rest on a piece of 1/4″ UV transparent acrylic directly on top of the aquarium itself).

From organism: ~6″ from the larger head, ~12″ from the smaller.

How often do you change bulbs? ~every 6-8 months when algal growth starts to become noticable.

ENVIRONMENTAL DATA (Rearing tank = observation dishes here):

Capacity: 100 ml

Dimensions: round 4″ diameter, 2″ high, with glass lid.

Filtration: None, daily 100% water changes.

Type of seawater used: Filtered (1 micron) aquarium water.

Frequency/Volume of changes: 100% daily

Success with rearing larvae in dishes: Low. Larval survival in plastic dishes floating within the aquarium itself was much better, and growth rates appear to be initially higher. I suspect that lighting has a lot to do with that success, and that if rearing dishes were as intensely lighted as
the reef aquarium itself, the larvae ought to do much better (but I have not tested this hypothesis).  

Comments: Reference used for scientific name; Dave Carlon, pers. comm.

Original description: Described by Esper in 1795. No other information available

Vernacular name: Star coral, moonstone coral (fr. Puterbaugh & Borneman), golfball coral

Word origin: The genus Favia is from the the Latin word favus meaning honeycomb; The species fragum appears to be from the Latin word fraga meaning strawberry. Despite the yellow to brownish coloration it could be seen from the shape and structure of the skeleton how Esper
might have described this species as a “honeycombed strawberry”.

Suggested reading:

Kaplan, Eugene H., A Field Guide to Coral Reefs of the Caribbean an Florida, 1982, Houghton
Mifflin Company, 2 Park Street, Boston, MA 02108, ISBN 0-395-31661-8

Veron, J. E. N., Corals of Australia and the Indo-Pacific, 1986, The Australian Institute of
Marine Science, University of Hawaii Press edition 1993, ISBN 0-8248-1504-1

Wood, Elizabeth M., Corals of the World, 1983, T. F. H. Publications, Inc., 211 West Sylvania
Avenue, Neptune City, NJ, 07753, USA, ISBN 0-87666-809-0

About this report: Information contained in this report is taken from submitted observations. Taxonomy, Synonomy, Original description , Word origin and Suggested reading are provided by member(s) of The Breeder’s Registry staff. Information is presented under the belief that it is accurate. If you have information in addition to, or contrary to that presented you are encouraged to contact the Breeder’s Registry. Permission is granted for “one-time” personal use. Reproduction as distributed or accessible media is prohibited without prior written permission. All rights reserved. 1997

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