An aquarium dominated by small polyp stony coral (SPS) is one of the most attention-grabbing reef biotopes. A reef aquarium filled with an assortment of SPS corals can be a striking display of shapes and colors. Many hobbyists are drawn in by SPS corals and welcome the challenge of some of the most demanding species. Having said that, an SPS tank can be difficult, and not every aquarist is looking for a challenge in what should be a relaxing hobby. An SPS-dominated aquarium can be a major hassle to maintain. If the reef tank is neglected by the aquarist for even short periods of time, the health of the corals can often take a swift downturn.
Luckily, it is possible to replicate the appearance of a traditional SPS reef with selections of much hardier SPS corals. When most people describe the requirements of an SPS system, namely high light, high flow, pristine water, and rock solid chemistry, people are taking the requirements for the most fragile varieties such as Acropora and Montipora and projecting it onto all SPS corals. In fact, it is possible to have an SPS dominated aquarium with vastly different conditions.
Here is a list of some hardy SPS corals:
Pocillopora, commonly referred to as cauliflower or brush coral, is a fast-growing stony coral with some variation in its growth patterns. Pocillopora damicornis, for example, is a branching colony that grows in a bushlike fashion. Pocillopora verrucosa, on the other hand, grows thick, club-shaped branches.
Seriatopora, or bird’s nest corals, are one of the most recognizable SPS colonies. They grow densely-packed branches that terminate in a sharp point. Seriatopora are one of the fastest-growing SPS corals. It is possible to grow a grapefruit-sized ball of bird’s nest coral from a 1-in. frag within 6 months.
Stylophora, commonly referred to as a cat’s paw coral, is a slower-growing branching colony. They closely resemble Pocillopora; however, Stylophora tend to have more rounded tips to their branches, and the spacing of the polyps appears more uniform compared to Pocillopora. Stylophora tend to grow more slowly than either Pocillopora or Seriatopora.
Porites, or jewel coral, comes in both a branching as well as an encrusting growth form. The branching colonies grow thick fingers that terminate in round, smooth tips. Branching Porites that are typically harvested for the reef aquarium hobby have a canary yellow color that makes this coral an immediate focal point in the tank. The feature of encrusting Porites that makes it stand out is it often hosts colonies of brightly-colored Bisma worms. Symbiotic relationships like this one between the worms and coral make the tank much more visually interesting.
Leptoseris, commonly referred to as a wrinkle coral, is a relative newcomer to the reef aquarium hobby. It was somewhat unknown in the industry until a few years ago and has since exploded in popularity, mainly due to its intense coloration. Most varieties are a combination of orange and yellow that are so vibrant as to almost look metallic. It is also found occasionally with a neon green appearance.
Meteor coral of the genus Cyphastrea is a great choice for an encrusting coral. They have brightly-colored polyps spaced uniformly throughout the surface, making for a unique aesthetic. Some of the most popular color morphs have heavy contrast between the polyp and skin, for example, red polyps against a blue background or yellow polyps against a purple background.
Scroll corals are not SPS corals per se, but they have plating growth forms that closely resemble that of Montipora. Some varieties of chalice are commonly mistaken for monitor when they reach full size. They are not very fast-growing compared to SPS, but provided favorable conditions can reach impressive size.
In conclusion, an SPS-dominant tank need not be very challenging. Many of the recommendations one receives to care for a traditional SPS tank stem from the requirements from two of the most challenging varieties, namely Acropora and Montipora. Those requirements do not necessarily apply to many of the other corals out there, so it is entirely possible to assemble a stock list of robust specimens that have much in common aesthetically with the more delicate species.