Montipora capricornis and digitata – Corals in Marine tank

The coral in this photo is Montipora capricornis which is a small polyped stony coral (SPS) of the Acroporidae family of Pacific Ocean corals. It is a common coral in the home marine aquarium because it is one of the more tolerant of the SPS corals to keep. Generally known by the shorter or more descriptive names of Monti cap or vase coral, leaf coral or leaf plate coral, and plate coral, this SPS coral requires moderate to high lighting (3 watts per gallon and up) and a high pH and high calcium levels to grow properly and prefers moderate to high flow rates of a fluctuating nature. Although the polyps of this coral might extract some nourishment from the water passing by the polyps, most of the coral’s energy needs will be met through a symbiotic relationship with the zooanthellate algae that exist in the coral’s cells. Generally, if this coral is getting too much light, it will expurge (kick out) some of the zooanthellate algae from its cells and, if it is not getting enough light, it will allow the concentration of zooanthellates to increase to the extent possible to increase the amount of energy being produced in its cells. The zooanthellates use a chlorophyll based process for converting the light into usable energy for the organisms.

Propagation of this coral by hobbyists is relatively easy and that is another reason why this coral is so common in the SPS marine aquarium. To propagate this coral, the hobbyist needs only to break off a fragment from the original and, using a cyanoacrylate based bonding agent such as Crazy Glue (TM), bond the fragment to a special marine plug or piece of live rock (LR). For many aquarists, the ‘breaking off’ process is the result of accidentally bumping the fragile plates while doing something else in the aquarium.

The piece of Monti cap in this photo began its new life as such a fragment about the size of a quarter and grew to about 10 inches in diameter before outgrowing its spot in the aquarium. At that point, it was fragmented and formed many new specimens which were then sold to other hobbyists. With plenty of light and water flow, the Montipora capricornis will develop a swirling multi-layered growth habit which can be very attractive.

As a moderately fast growing coral with more tolerance than most SPS corals, this is an ideal coral to begin with for those who want to try keeping SPS corals. Be aware though that, like most SPS corals, the Monti caps still require more light and better water conditions than the soft corals.

The darker green coral in the banner and behind the Monti cap in the photo is Montipora digitata. This Montipora sp. is referred simply by its scientific name or sometimes as Velvet Monti. When the polyps are extended, the coral piece can appear as if it is covered in velvet or can appear like the ‘velvet’ covered horns of a deer.

The growth rate of Montipora spp. can sometimes be quite rapid if water and lighting conditions are optimal. This can result in one coral encroaching on the other. Corals compete for space using chemical and physical weaponry (stinger cells) and, among the Montipora sp., the green variety of the Montipora digitata is quite capable of holding its own, as can be seen by necrosis-like damage at the margin of the Montipora capricornis in the photo where the two species have grown into each others’ space.

Various sources suggest various “ideal’ water parameters for the Montipora species of SPS coral with most suggestions being in the range of Calcium 400 – 450 mg/l, pH 8.1 to 8.5 and a Specific gravity (SG) of 1.023 to 1.025.

The pictured specimens were growing near the top of my marine aquarium receiving illumination 10-12 hours per day from a 50/50 combination of t8 Daylight (6500K) and actinic tubes. Most aquarists would consider this to be too low for SPS corals, even the Montipora species, and would opt instead for t5 HO and metal halide lighting. Such lighting intensities would certainly allow for the corals to prosper at deeper levels in the aquarium.

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