The aquarium hobby in general, and certainly the reef aquarium hobby in particular, has changed a whole lot over the years and decades. As aquarists master the husbandry of new species, some “classic” species might lose their luster. For example, where Xenia was once a beloved coral for its ease of care and pulsing behavior, …
Corals
Corals are a group of exclusively marine, polyped animals in the phylum Cnidaria. As one can see from their basic body form, they are distant relatives of jellyfish. They can take the form of either individual polyps or colonies of perhaps hundreds or thousands of individual polyps.
They are divided into two basic groups, namely the hard corals and soft corals. Some may be surprised to find that these two groups aren’t very closely related; in truth, stony corals are more related to “normal” anemones whereas soft corals are more related to tube anemones (i.e. cerianthids).
They occur in many ocean habitats from deep waters, temperate waters or shallow tropical waters. However, it is the latter type that most aquarists are familiar with. It is in tropical reefs that stony corals predominate. These produce a hard, stone-like skeleton made of crystalline calcium carbonate called aragonite. They are the so-called reef-building types and are primarily responsible for the formation of the reef itself (the crusts, shells or tubes of certain algae, mollusks, worms, etc., which are also made of calcium carbonate, make some smaller contribution). Chunks of these deposits are known (especially by aquarists) as live rock.
Soft corals, including the gorgonians and sea fans, produce no such calcium hard skeleton. They may, however, produce a leathery (e.g. leather corals) or horny (e.g. gorgonians/sea fans) “skeleton.”
Most reef-building corals and many tropical soft species have a mutually beneficial relationship with special unicellular algae (called zooxanthellae). These algae live within the host’s gastrodermis. Up to 90% of the carbon fixed by the algae via photosynthesis is taken up by the coral. Similarly, certain bacteria known as diazotrophs supply a source of fixed nitrogen to the animal and its algal symbiont, and in return feeds on their organic waste products. Increasingly, the coral animal and its many, diverse microscopic partners are viewed as a single super-organism referred to as the coral “holobiont.”
In addition to these symbiotic relationships, many prey on zooplankton or even tiny fish (depending upon species and size). The coral uses its tentacles, armed with stinging cells (i.e. nematocysts) to stun, hold and kill its prey as it moves the item into its mouth. Following digestion, the waste is excreted from the same opening.
Success with these fascinating and beautiful creatures in captivity requires regular feedings of each species’ preferred food source(s) as well as intense illumination to promote photosynthesis of the zooxanthellae.
In this section you will learn which corals prefer which types of light and foods, as well as how to create the environment (e.g. water conditions) that they need to survive and grow.
Keeping Toadstool Leather Corals
These days, soft corals don’t get quite the attention they once did. One reason for this simply is the abundance of wildly colorful stony corals that have fairly recently become available. Another reason is the concern that soft corals can release allelopathic substances into the water that may harm other (especially stony) corals. Even so, …
Upgrading to the ULTIMATE Ecopack
Pods. Phyto. At AlgaeBarn, these are the bread and butter of the reef aquarium diet. And for sure, these two items form the base of most freshwater and marine food chains. Just consider OceanMagik, which is a blend of four distinctly different species of phytoplankton. Or EcoPods, which is a mixed-species (four, to be exact) …
Do Corals Really Eat Plankton?
It’s hard to say for sure which came first for reef aquarists–the emergence of high-quality coral foods, or the realization that corals actually, really, truly do eat them. Though aquarists are generally a skeptical bunch, the initial apprehension to feeding corals is pretty understandable; in all fairness, many such foods sold in the recent past …
Natural Water Quality Management for Non-Photosynthetic Reef Aquaria
There was once a time when zooxanthellate corals (especially SPS corals) were considered impossible to keep in captivity. Then advancements in aquarium lighting technology changed all that. It’s hard to imagine that there so recently was a day when marine aquarists abandoned the possibility of ever keeping Acropora–one of the most abundant genera of stony …
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What Do I Need for a Saltwater Fish Tank?
Whether scouting for your first aquarium, or “graduating” from a freshwater aquarium, there is something about a saltwater aquarium that is mesmerizing. For many lifelong aquarists, that feeling of captivating awe never goes away. Thankfully, the intimidating task of learning how to actually build and maintain a saltwater aquarium system does go away. In fact, …
Keeping a Coldwater Marine Aquarium
Marine aquarists have always had access to temperate species. In fact, in the days before improved packaging/shipping procedures allowed for the massive import of tropical species that we enjoy today, most saltwater aquarium livestock originated from temperate waters. Catalina gobies, waratah anemones, garibaldi damsels… At least half of the seahorses… The coolest boxfishes… Anyone who …
Knowing the Zoanthid
The zoanthid is one of the most stunning yet simplistic coral-like animals in this hobby. It can come in any color combination that you can imagine–along with any price point. This is why this particular anthozoan deserves an article of its own. There are over 100 species of zoanthids alone and the identification process can …
3 Most Expensive Corals
For people that are new to this hobby, it is sometimes hard to grasp just how expensive certain corals can be. In this article I will be discussing the most expensive corals (well, corallimorpharians and zoanthids, to be technical) and the reasoning behind the price. Most of the time, the price is due to high …
How to Get Rid of Aiptasia
When you’re first starting out your aquarium, you usually will spend all day checking on everything in your tank ensuring everything is still intact. Then, one day you look and you see this translucent looking pink flower… I receive one of two reactions from customers when they first come across Aiptasia anemones. One is panic. …
When to Choose Poseidon’s Feast
Back in “the day,” to acquire a seed culture of copepods, aquarists would typically have to resort to scooping a couple cups of gravel from the bottom of a fellow aquarist’s tank. In these cases, you could only hope to have nabbed a few viable pods–and not any pests (like juvenile aiptasia anemones)! If you …
Three Great Hacks for AlgaeBarn Simple Brine
For about a century, brine shrimp (Artemia spp.) have been among the most important of all aquarium foods. Not only are they extremely nutritious, and fish love them, but they are also incredibly convenient to use. This is because it is relatively simple to store and hatch their cysts. Cysts are unlike eggs in that …
The Whole Package: Integrating AlgaeBarn’s Kits & Combos
AlgaeBarn is hardly the only aquarium hobby-centered business to produce phytoplankton and macroalgae. But we like to think that we’re pretty darn good at it–if not the best! Consider our highly-acclaimed premium live phyto blend OceanMagik in various kits or our standard-setting CleanMacro series. If it needs to be stated, algae is kind of the …
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Keeping Zoanthids
Reef aquaria wouldn’t be reef aquaria without corals–plain and simple. But those extra little goodies (sea anemones, corallimorpharians, etc.) undoubtedly make reefkeeping a lot more interesting. This could certainly be said of the zoantharia. Indeed, as novel color morphs of popular species continue to be imported, aquacultured and distributed within the trade, zoanthids are increasingly …
Keeping Mushroom Anemones
No one starts a saltwater aquarium because they hate challenges. Indeed, it is the difficulty (or at least perceived difficulty) of maintaining these systems that is so alluring to many first-time marine aquarists. That being said, it’s always good to take the stroll towards full-blown reefkeeping in baby steps. Veteran hobbyists have seen it so …
What’s the Difference Between PNS ProBio and PNS YelloSno?
Reef aquarium keeping has gotten a lot more sophisticated over the years. Fortunately, that doesn’t necessarily mean that it has gotten more complicated or more time-consuming. To the contrary, we now have the knowledge to create convincingly realistic representations of coral reef habitats with surprisingly minimal effort. While it’s true that we’ve now got some …
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A Closer Look at Coral Tissue Necrosis
Whether you are a dedicated, full-time coral farmer or a moderately invested hobbyist, reef aquarium keeping is risky business. This is due partly because of the inherent delicateness of corals in general, but also because coraliculture is still a relatively young (sometimes downright experimental) undertaking. Coral disease–and disease control–remains as one of the most poorly …
Gorgonians in the Marine Aquarium
It should go without saying that the hermatypic, stony, reef-building corals will dominate most reef aquaria. Thankfully, so long as (1) key water parameters are monitored, (2) the appropriate light conditions are provided and (3) nutritious planktonic foods are present, these beautiful plant-animal symbiotic combos easily flourish even in the care of novice hobbyists. Especially …
Enhancing Coral Nutrition with Purple Non-Sulfur Bacteria
Most people who are familiar with corals–whether admiring them in the wild or displaying them in a glass box–understand quite well that they are incredibly complex animals. This certainly is so with the zooxanthellate corals. Virtually all corals (zooxanthellate corals included) are predators of plankton and other tiny organisms. But the zooxanthellate types undoubtedly are …
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A Quick Guide to LPS and SPS
There comes a time in this hobby when many aquarists grow bored of their beginner corals and they become interested in small and large polyp stony corals (SPS and LPS, respectively). For those of you who have been maintaining a “softie” reef (which includes coral such as zoanthids, mushrooms, leathers, and star polyps), you may …