Corals to Avoid

Adam Blundell M.S.

Background

The coral family Nephtheidae contains several species commonly found in the aquarium trade.  Some of these corals are very well suited for home aquaria, but unfortunately some are not.  This article is a synopsis of the experience of hobbyists with the genera Dendronephthya and Scleronephthya (please note that this is the correct spelling, as it commonly misspelled in publications and journals). 

Historically these two genera have been difficult if not impossible to keep in captivity.  Often alluring with vibrant colors, one cannot blame hobbyists for wanting to give a try at these corals.  In fact the author would love to solve their husbandry issues as these rank high on my list of personal favorite corals.

Biology- (for in depth information please see Borneman 2001 and Sprung 1999)

Dendronephthya/Scleronephthya are filter feeding corals.  Voracious filter feeding corals that is.  These corals completely lack the symbiotic zooxanthellae found in most corals.  The pro to that is that these corals are presumably more tolerant (and hardier) than most other corals.  For example these corals can withstand environmental changes without the possibility of coral bleaching (Kaufman 2004).  These corals continuously reproduce and rapidly populate areas with favorable conditions (Siegel 2002).  Unfortunately the pros of these corals are dwarfed by their cons.  Without the aid of photosynthetic zooxanthellae these animals are dependent on large amounts of plankton.  That is beginning (and the end) of their captive demise.  Simply put, for now these corals are impossible to keep in captivity.    

Dendronephthya/Scleronephthya are easily found and identified (in a general manor) on reefs.  Their vibrant colors and large sclerites are quick to catch the eye.  The sclerites serve to hold shape, and also contribute to the defense mechanisms of this coral (which includes a high concentration of toxins).  It is possible that sclerites aid in gas exchange but that has yet to be well studied.

These corals are found in waters (doing best) with flow rates between 5 cm/sec and 25 cm/sec (2 in/sec and 10 in/sec).  The feed heavily throughout the day and in captivity always require heavy feeding.  This continuous feeding cycle may correlate to their ongoing reproductive mode. 

Previous Experiments-

Before you think that you can keep these corals let me say this; it’s been tried before.  That isn’t to say that hobbyists won’t be successful with these corals in the future, but for now it would highly irresponsible of me to encourage people to experiment with the husbandry of these corals. 
The most advanced efforts to captively keep these animals have been performed by the Waikiki Aquarium and the Long Beach Aquarium of the Pacific.  This information is well documented and can be found in the online article in the references below (Delbeek 2003).  These two well maintained aquariums used a slurry of phytoplankton foods, supplemented with zooplankton.  Great efforts have been made to create laminar flow recreating tide patterns along reef drop offs (Delbeek 2002).  Coral attachment was also explored and anecdotally showed that hanging the corals upside down so that the branches do not touch substrate improved coral health and growth. 
However, long term success has still yet to occur.  With an incredible amount of feeding an aquarist needs to provide an incredible amount of filtration.  Public aquaria have the option of using flow-through systems which so far seem to be the only filtration method able to keep up with the high nutrient load.

Conclusion-

At this time while enticing to purchase Dendronephthya/Scleronephthya are still not a coral to be purchased.  The extreme feeding techniques of these animals is not practical (or maybe even possible) in the home aquarium.  Future husbandry advancements may help, but for now these organisms are to be avoided.

Author Information-

Adam Blundell is the president of the Wasatch Marine Aquarium Society.  Comments and questions are always appreciated and welcomed at adamblundell@hotmail.com.  You can find Adam at www.UtahReefs.com.  This article was sponsored by the Aquatic & Terrestrial Research Team.

References and Suggested Readings-

Borneman, E., (2001) “Aquarium Corals selection, husbandry, and natural history”, T.F.H. Publications, Neptune City, NJ. USA.

Delbeek, J.C., (2002) "Non-photosynthetic Corals: They really are hard!”, http://advancedaquarist.com/issues/jan2002/feature.htm , Advanced Aquarist Online Magazine, USA.

Kaufman, L., (2004) “Fiji’s Rainbow Reefs”. National Geographic, USA.

Siegel, T., (2002) “Struggling with Alveopora and Dendronephthea”, http://advancedaquarist.com/issues/oct2002/Editorial.htm , Advanced Aquarist Online Magazine, USA.

Sprung, J., (1999) “Corals a quick reference guide”, Ricordea Publishing, Miami, Fl. USA.

WetWebMedia publications- http://www.wetwebmedia.com/dendrofaqs.htm