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Related FAQs: The Fishes of the Red Sea

Related Articles: Reef Flats, Sandy Reef SlopeBiotopes, Fishwatcher's Guide to the Red Sea, Triggerfishes of the Red Sea, Butterflyfishes of the Red Sea, Angelfishes of the Red Sea, Anthiinae,  

Marine Aquarium Biotopes: Pt.2

 Red Sea Reef Slope  1 of 5

Bob Fenner

The junction between the reef flat and slope can be breathtakingly sharp

Reef Slopes of the Red Sea:

    These are regions of drop off from reef flats/plateaus of principally rock and mineralized skeleton make-up. As with reef flats in the Red Sea, the Slopes occur almost continuously along the coast line and few island masses. Most (99 %) are a few to several meters in expanse, with a few areas actually sandy beach (e.g. Na'ama Bay, Sharm) and fewer still represented by drop-offs of dozens to hundreds of meters in depth (e.g. Ras Mohamed). Most slopes are steep, vertical to at least sixty degrees, with little taper, presenting restricted light conditions for all but the top lip of the slope. 

About Red Sea Reef Slopes:  Make-Up, Features of Aquarium Importance

     Flow rates for current are likewise reduced locally. Appreciated by divers in high water movement conditions is the "micro-climate" of diminished water flow at/near the reef slope face itself. Typical water movement in aquariums (non-linear, a few to several times per hour turnover) are fine for these displays.

    As with most Fish Only with Live Rock (FOWLR) to reef displays, a careful stacking of larger (two fist size and larger) rock with large openings in a more vertical arrangement are desirable.

Images of Red Sea Reef Slopes showing characteristic traits. Near-vertical faces of rocky composition, low light other than upper lip, predominance of principal life forms: hard, soft corals, Milleporina, Orange Anthias Basslets.

Video of Sandy Red Sea Reef Slopes:  to be done: place link to video at right, instructions to right click icons.  

Biota of the Reef Slopes of the Red Sea: A Rough/Inexact Delineation But Useful

    Here we will list and describe the species of most use and availability to aquarists. Of course there are many more species than can be practically detailed here and some species that should not be offered to the hobby do make their way into markets. As a precautionary measure we'll include a table of ones that are often for sale, but shouldn't be due to historically dismal survival records. 

Most Common Species of the Red Sea Reef Slopes

Misc. encrusting Red Algae, filamentous Greens. Same as the reef flat/plateau, with a sprinkling of other species: Here's a nice patch of encrusting Red Algae with the soft coral Parethropodium fulvum on its left.
Sponges of various sorts, encrusting, globular to tubular occur sporadically. Most are small, inconspicuous, though there is the occasional spectacular specimen that "rises out" off the hard substrate. The hobbyist is most likely to encounter encrusting species like Spirastrella coccinea (shown), though the Red Sea is home to all Classes of Poriferans, some tubular, some arborose, others vase and globular in shape.
Pocilloporids (Cat's Paw Corals) and Acroporids (Staghorn Corals). The genera Acropora, Porites, Seriatopora, dominate here.
Soft Corals, particularly "tree like" Litophyton, Toadstool like Sarcophytons, occasional rubbery when closed Sinularia (Shown S. polydactyla) in upper, better lit regions of the slope. In lower, slower current areas you'll find Pulsing Corals, family Xeniidae of various species predominate and occasionally some dazzling Dendronephthya
Fire Coral, Millepora spp. A ubiquitous genus in the Red Sea. Occurring as larger branches, encrusting forms and even pillars growing on any, all hard surfaces where not out-competed by other life.
Giant Clams, There are some T. crocea here as well, but mainly you find Tridacna maxima (Pictured). T. squamosa also occurs in the Red Sea; it's mainly found further down on the sandy slope. 
Orange Anthias, Pseudanthias squamipinnis, THE most common, make that "poster child" organism of the Red Sea. Shoals of males and their harems are found throughout the region. Other species of Anthiines occur in the region (see below), though only one other in abundance. For aquarists these fishes live in haremic associations, one or two males (if you have hundreds of gallons) with as many females as you like. If the male/s perish, a female will convert to replace it.
Butterflyfishes; Chaetodon semilarvatus, C. paucifasciatus (shown), C. auriga, C. fasciatus and Heniochus intermedius "visit" the reef flat for short feeding forays (or to avoid divers) but are more often encountered on the reef slope, dipping in and out of overhangs and rocky caves.  
Basses of various sorts (other than the omnipresent Anthiines), family Serranidae. Some one is always lurking about. All a diver has to do is turn their head to spy the hallmark delta shaped eye of a serranid keeping their eyes on them. A handful of species that are found in the Mares Rouge are imported to the trade. Some are real winners for folks with big enough systems. 
Tangs, family Acanthuridae, particularly the Naso (lituratus) and Purple Tang, Zebrasoma xanthurum, Z. desjardinii (Pictured, a ten inch one in the Red Sea)... though a few others are common and useful enough to be mentioned.
Angelfishes; mainly juvenile Pygoplites diacanthus, Centropyge multispinus (darting out of sight most everywhere) and the occasional Pomacanthus imperator and P. maculosus are seen here. Other species of pomacanthids are found in the Red Sea, but are rarer especially on reef slopes. Though not common in the wild, do look for the now-almost-available everywhere cultured P. asfur's (see below)

Species Offered Occasionally from Red Sea Reef Slopes but Should be Avoided  

Gymnothorax javanicus, the Giant Moray Eel. To three meters in length. A fish, then crustacean eater... and biter of humans when provoked. 
Coral polyp feeding Butterflyfishes: Chaetodon austriacus, the Exquisite Butterflyfish. Along with some other Red Sea Butterflyfishes (Chaetodon pictus, C. melapterus, C. larvatus, C. lineolatus, C. trifascialis) which are thankfully rarely offered in the aquarium trade this species is sold from time to time, and is a virtual obligate corallivore, making live coral polyps its principal food source. 
Sweetlips, family Haemulidae, subfamily Plectorhynchinae. No less than nine Sweetlips Grunt species call the Red Sea home. Other than Plectorhynchus gaterinus (pictured) which has only a marginal survival rate, most all species die soon after introduction (if not before, enroute) to captive conditions. 
The Black and White Snapper, Macolor niger. Some friends in the wet pet industry and other authors give this fish grand marks, but I have yet to see a juvenile of less than five inches live for any length of time. Make sure the one you are buying has been around a few weeks and is feeding. Juvenile shown.
Sargocentron spiniferum, the Sabre or Giant Squirrelfish. A beauty, but often lost to trauma in capture and shipping and too large for most systems (to eighteen inches in length). 
Conus textile Linnaeus 1758, the Textile Cone. Indo-Pacific; Red Sea, much of the rest of the tropical Indo-Pac. Feeds on other prosobranch snails. Can be fatal to humans. Red Sea image. This and the equally venomous C. geographus are sold into the trade from time to time... and should not be.
Dendronephthya spp. (D. hemprichi, D. klunzingeri in the Red Sea). These Soft Corals are often breathtakingly beautiful in fluorescent reds, greens, oranges, purples... but have absolutely dismal survival histories in captivity. Attempts are being made, experiments by public aquariums as to what these Alcyonaceans nutritional demands are... dissolved organic carbon, nano-plankton? Shown: "classic" view of the cargo container from the wreck at Ras Mohamed.

Survey of Best, Available Species of Red Sea Reef Slopes:

Algae: There are no large stands of Red, Brown or Green Kelps in the Red Sea, but quite a few encrusted and attached forms of these Divisions can be found, and employed by aquarists, most of a distribution encompassing the Indo-West Pacific. 

Actinotrichia fragilis (Forsskal) Borgeson 1932, Spikeweed. Close up and colony images, in the Red Sea. 

Galaxaura sp. (maybe G. marginata) in Hawai'i and a bleached-out colony in the Red Sea.

On to: Red Sea Reef Slope 2 of 5

On to/down the slope to:

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