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 Australomussa Coral Care



 Taxonomy

If you have never heard of this coral, it is understandable. They are an uncommon coral in the trade to begin with and are not often talked about online. Furthermore, they go by different names. These corals are imported as Australomussa rowleyensis however researchers reclassified them about 5 years ago into the genus Parascolymia. This genus sounds vaguely familiar doesn’t it? Sounds like “Scolymia” and the “para” prefix has a few different meanings, but roughly translates to adjacent, near, or resembling, so the term “Parascolymia” would indicate something “close to Scolymia.” These corals though only have a passing resemblance to what are normally thought of as Scolymia in the hobby which tend to be a single polyp and a bit more fleshy in appearance. That observation wasn’t lost on coral taxonomists either and as such, the ever popular Scolymia australis was bumped into the genus Homophyllia. Also bumped into Homophyllia were corals that were once Acanthastrea bowerbanki and you can see more of a resemblance there between the two.

You might be thinking, what is even left in the Scolymia genus if the australis species was booted out? Well for one, it leaves Scolymia vitiensis, and now THAT looks a lot more like this Parascolymia/Australomussa. They both have this very flat growth form with large polyps and a spiky skeleton that you can get a hint of on the surface of the coral.

For the sake of this blog I am just going to call them Australomussa. A few people know this coral by this name, but almost nobody knows it by Parascolymia. Who knows, by the time you read this blog, it might be reclassified again, so I am not exactly married to these labels. Like I said before, this is one of the coral categories that has seen a lot of shuffling recently, and could see more in the future.

Taxonomy aside, Australomussa is a very uncommon large polyp stony coral in the hobby.

 Location

As the prefix of this coral's name may hint at, this coral can be found in the southern parts of the world, specifically Northern Australia and parts of Indonesia.



Now that we’ve gone over some background info on Australomussa, let’s dive into their care requirements.

 Lighting

Australomussa are photosynthetic corals, meaning they get nutrients from the products of photosynthesis carried out by symbiotic dinoflagellates called zooxanthellae living in their flesh. Zooxanthellae utilize chlorophyll to absorb light and produce simple sugars that the coral can utilize for energy. Some corals rely on this energy source more than others and will need brighter lighting.

Australomussa however tend to be less demanding of light intensity and may actually fare better in dimmer tank conditions. We try to place Australomussa in low to medium light intensity in our tanks here at Tidal Gardens which is around 50 to 100 PAR. If your tank is higher in light, it will take some time for this coral to adjust to its new surroundings. When in doubt, try lower lighting intensities until it is clear that the coral is stable before ramping it up.

Remember that lighting that is too bright risks damaging the coral, and this damage can happen quickly. If you start to see the coral starting to turn lighter and bleach out, it is time to move it to a dimmer location. It is possible to for a Australomussa that has bleached to recover but it can take a long time. During this time it may also retract tight against its spiky skeleton and the tips might poke through the skin which can lead to other health problems.

If your coral did retract and bleach, what may help is to relocate it to a low light area of the aquarium and aggressively feed it.

Aside from the nutritional aspects of lighting, let’s consider the aesthetics.

Australomussa do fluoresce, but not as intensely as some other corals. Their appearance however does change substantially depending on the color temperature of the lighting provided. What looks best is a matter of personal opinion. I like them in a slightly more blue lit tank around 14,000K to 18,000K. When the color temperature is warmer in the 10k range, I think some of the colors I like are drowned out in the daylight.

Mind you we are talking about the presentation of the coral for viewing not the actual color of the coral. Australomussa do not appear to change color very much as their coloration remains relatively consistent. Some corals such as Micromussa can really color shift but that’s not so much the case with Australomussa.

Low Light

Low light translates to about 30-50 PAR

Medium Light

Medium Light is between 50-150 PAR

High Light

High Light is anything over 150 PAR

Lighting is a loaded topic, so for a more in-depth discussion of lighting, please see our Deep Dive article.



 Feeding

While it may be possible to get away with keeping Australomussa with lighting alone, I think this coral benefits greatly from consistent feeding every 2-3 days. Corals that are well-fed grow faster and can handle stressful conditions better than corals that are malnourished.

They can be fed either frozen food or specialized LPS dry foods. The problem with feeding Australomussa is that it is not the most aggressive feeder. Feeding takes some patience because it takes some time for it to start eating and then care must be taken to allow it to actually consume the food. We have the best luck turning off all the flow in the aquarium and then giving it a light dusting to activate what little feeding response they have. After a minute or two we can then put some larger pieces of food on them and allow them to eat it over the next 10-20 minutes

During this time if you have fish or inverts around, they may eat the food sitting on the coral which is clearly not helpful. The bigger concern with feeding is that certain fish and inverts such as shrimps and crabs can cause major damage to a coral when they go after the food. Fish stealing food out of the coral’s grasp is one thing but if you have tank mates that rip a coral apart to get at the food, something more drastic has to be done.

There are a few different ways to try and combat this. When it is time to feed your corals try feeding the fish and other critters in advance. Give the herbivores a fresh clip of Nori on the opposite end of the aquarium. If you keep the fish occupied the coral should have time to digest its meal. If that isn’t successful another option is to create a feeding barrier. You can DIY something out of a container or you could go with a commercially produced feeding cage. If you want to get even fancier I am sure there are plans on the internet for 3D printed coral cages that would allow for feeding corals.

 Flow

Australomussa appreciate low to medium flow. There are two things that I am looking to accomplish with flow for this coral. The first is to give it enough flow to keep it clean. Detritus build-up can cause the coral to die back where it collects. Providing flow around the coral can prevent this accumulation. Even moderate flow can serve to keep the coral clean as the coral does a good job of slugging off debris that settle on it.

Too much flow will cause its flesh to be drawn tight to the skeleton all the time which again is a very bad thing considering how spiky it is. Worst case scenario, the skeleton pokes through the skin and starts to grow nuisance algae.

Providing periodic low flow or even zero flow is beneficial for this coral for the purposes of feeding. I actually prefer completely turning off the flow to feed Australomussa because its flat shape really deflects any flow directed at it which would prevent the food from settling down on it.

 Chemistry

As for chemical parameters for this coral, Australomussa doesn’t have any unique requirements that set it apart from any other LPS. There are pollution parameters to look out for, and the three main building block parameters.

Starting first with the pollution parameters, the two main ones to keep track of are phosphate and nitrate. Phosphate and Nitrate are great general measurements of water cleanliness. They show up mainly in the food we provide the tank but decaying plant and animal matter in the aquarium can also elevate their levels in the water.



We generally shoot for about 5-10 ppm nitrate and .05 to .1 ppm phosphate.

If Nitrate levels get too high corals may react negatively by taking on drab coloration or suddenly dying back in extreme cases. If Phosphate levels are too high, it may feed into an unwanted algae bloom or spur on the growth of other undesirable organisms that can stifle the growth of corals.

For a short period there was a push in the hobby to have near zero levels of nitrate and phosphate. This is done through techniques like carbon dosing or GFO which can aggressively bring those numbers down. Ultra low nutrient levels though come with their own sets of issues. There is such a thing as too clean and I would argue the problems caused by near zero nutrient levels are much worse than those caused by an abundance of nitrate and phosphate.

Corals require some level of nitrate and phosphate available to them. When starved out, the corals first take on a shrunken emaciated look and then they start dying off. After that there is a risk for blooms of unwanted organisms such as brown dinoflagellates that thrive in ultra low nutrient conditions.

For Australomussa specifically, I would rather see Nitrate and Phosphate levels on the high side than barely detectable because we have kept them in systems with very high nutrient with little to no difficulties.

Moving on from the water cleanliness parameters, let’s consider building block parameters, Calcium, Alkalinity, and Magnesium.

Because Australomussa are stony corals, these are the three major chemical parameters that are needed by the coral to build its skeleton.

Starting first with Calcium… Calcium is one of the major ions in saltwater. In the ocean, its level hovers around 425 parts per million. As a coral grows calcium is absorbed from the water and used to forms its calcium carbonate skeleton.



Alkalinity a collection of ions that generally equate to carbonate availability in the water. Technically it is the amount of acid required to lower the pH of saltwater to the point bicarbonate turns into carbonic acid. If you have more alkalinity, it can soak up more acid. Less alkalinity and you have less buffering capacity making the tank more susceptible to chemical changes.

In natural sea water, the alkalinity of the water measures around 7 or 8 dkh though most salt mixes these days mix up closer to 8 to 9 dkh. Some aquarists like to overload this parameter a little and keep their tanks around 10 or 11 dkh under the belief that having elevated calcium and alkalinity in the water contributes to faster stony coral growth. In practice alkalinity tends to be the parameter that fluctuates the most, so if you can only manage to test for one parameter frequently, test for alkalinity.



Last point I will make about water chemistry is that stability is the goal. Even if one or two parameters are “off” a little bit, it is better for you to remain consistent at that level than for you to try to change the values trying to hit a particular target value. Here is where keeping an eye on Magnesium can help. Raising both calcium and alkalinity together can be tricky because calcium ions and carbonate ions want to react with one another. Addition of a calcium supplement often comes with a corresponding fall in alkalinity levels and vice versa. If you are experiencing this in your systems, small fluctuations are normal, but wild swings are not. If you are experiencing dramatic swings of calcium and alkalinity every time you use an additive, you may want to look at your Magnesium levels. In short, Magnesium acts to increase the overall bioavailability of alkalinity compounds in the water evening out the chemical swings. In the ocean, Magnesium sits at about 1350 ppm.



I have to point out though that Australomussa is a very slow growing stony coral and isn’t likely the cause of any fluctuations you might be seeing. There are some very fast growing stony corals out there that can singlehandedly drop your levels as they grow, but Australomussa is not one of them. I bring these parameters up because stability in your water chemistry is what you want to shoot for and if done right will give you the best chances for success of not only this coral but all the others in your tank.

That should give you a little bit of background on the chemical parameters to keep an eye on.

 Aquaculture

So now that we have gone over the care requirements for Australomussa, can we breed them, or frag them?

This simple answer is maybe depending on what your expectations are. Australomussas are an extremely slow grower, so if your goal is to cut off a piece of a larger colony to share with a fellow hobbyist, that is possible. They can be cut and healed with something like a diamond blade band saw.

If we are talking about commercial aquaculture, propagation likely isn’t the solution because it would take entirely too long.

One future solution may well be sexual reproduction and with the advances in the area happening rapidly it really isn’t out of the question although it would require a considerable grow out area for a long period of time, which would undoubtedly result a huge price increase. Sexual breeding could also potentially produce some interesting hybrids and color morphs so maybe in boutique operations that might become a thing.

 Conclusion

Ok, that about does it for Australomussa. So what kind of tank is Australomussa best suited for? I see Australomussa as a show-piece LPS for hobbyists that are looking for something different. Not too many people are even aware of this particular coral and there are some amazingly beautiful examples out there.

Hopefully this blog is helpful for those looking to try them for the first time. If you would like more information or perhaps purchase Australomussa for your home aquarium, I invite you to visit our LPS page and see what we have in stock. We are always on the lookout for new and interesting color morphs of this coral to add to our collection, and hopefully yours as well.

Until next time, Happy Reefing.


Than Thein

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