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If you just got a new Acan coral for your reef tank and are wondering how to care for it, read on! Acan corals are one of the most popular types of coral in the hobby. They come in many colors and shapes, so if you’re looking to fill up some space with color, this is a great option. Let’s go deeper with the essentials on Acan Coral Care so you can have a thriving colony yourself!
A Quick Overview On The Acan Coral
|Scientific Name||Acanthastrea spp.|
|Common Names||Acans and micros, largely named after their designer names|
|Origin||Widely found throughout the Indo-Pacific (Fiji, Australia, Tonga, Solomon Islands) 1|
|Common Colors||Purples, blues, greens, oranges, yellows, reds|
|Lighting||Low-Moderate (50-150 PAR)|
|Tank Placement||Bottom, Middle|
|Temperature Range||76-82 degrees F|
|pH Range||8.0 – 8.4|
|Salinity||1.025 or 35 PPT|
|Alkalinity||8 – 12 dKH|
|Calcium Level||350 – 450 PPM|
|Magnesium Level||1250 – 1350 PPM|
Origins And Habitat
Acan corals originate from the tropical waters around Fiji, Australia, Tonga, and the Solomon Islands. They form large colonies often found on the seabed or near the bottom of the rockwork of shallow reefs (30-50m).
Most acans available within the hobby today come from Australia. However, these corals are popular to aquaculture because many wild acans arrive with bacterial infections; aquaculture also gives better control over color expression and subsequent designer names as well as growth rates.
Taxonomy And Naming
Acan corals are abbreviated after their taxonomic genus, Acanthastrea. There are several large polyp stony coral (LPS) species within Acanthastrea, though only Acanthastrea echinata and Acanthastrea bowerbanki are widely kept in the saltwater aquarium hobby.
Micromussa lordhowensis (named after their discovery near Lord Howe Island) used to be classified under Acanthastrea, but was recently moved to the Micromussa genus. Now, these corals may still be referred to as their popular name, acan ‘lord’, or simply called micros. It’s an LPS coral with lots of hobby names!
What Do They Look Like?
An Acan coral is easy to identify, though their flattened, suction-cup appearance can sometimes resemble Blastomussa spp., species of brain coral (Mussidae and Merulinidae families), or even chalice corals (Echinophyllia spp.). Their fleshy polyps as a lot of interest contrast other corals in the display tank.
In general, acan corals form tight colonies with puffy outer rims and deeper, flatter centers. The outside is usually a different color from the inside and might display a gradient of color. In healthy and/or hungry acan coral colony, clear tentacles will be visible along the inner rim of the mouth. A single acan coral polyp typically stays under an inch in diameter when fully grown, but larger species may be closer to two inches.
The different species of acan corals can be difficult to tell apart from each other, though their requirements in reef aquariums are all relatively similar. Here are some ways to tell the most common three species apart:
- Acanthastrea echinata is most commonly found in variations of red, orange, and green, but may be found in other colors as well. These corals are in between M. lordhowensis and A. bowerbanki in regards to the size. They have a smooth appearance and are flatter than these other species as well.
- Acanthastrea bowerbanki is the largest species of acan coral out of these three. They are flattened and have a bumpy texture. In colonies, they take on irregular shapes.
- Species of Micromussa lordhowensis are referred to micros due to their small size in comparison to the two other species. These are some of the most colorful acan coral and can come in many different colors and patterns.
As mentioned before, the acan coral is largely marketed based on appearance. Some of the most desirable acan corals show the best colors, like ‘rainbow’ and ‘ultra’ variations.
Placement And Temperament In The Aquarium
These corals are not demanding and can thrive in places of the saltwater aquarium where other species might lack light. However, their colors, size, and growth rate largely depend on the type of light they’re being kept under as well as how often they’re being fed.
An Acan coral are a low to moderate light coral, which means that they will do best on or near the sandbed. They need moderate water flow to keep food moving past their clear center tentacles and to keep debris from building up in between the colony. If given ideal conditions with room to grow, they will quickly take over an isolated rock island.
However, can acan coral can be very aggressive even though they lack the long sweeper tentacles of other LPS corals. Some hobbyists choose to keep them on the main rockwork of the display, but this can quickly become a problem once the acans get close to other corals; allowing the acan coral to grow on the rockwork also creates a flatter shape whereas they will create a more circular colony on an island.
Different species of acan coral should not be placed together. Unlike other corals that are compatible within the same genus, members of Acanthastrea are incompatible with each other and will start to attack the other if placed too closely together.
Do They Like High Light?
Acans can actually be kept at most levels of the reef tank. However, they vary in size and color under different lighting conditions. An acan coral kept under LED lighting will look much different from one kept under T5HO lighting. This can be tricky purchasing an acan coral in-store or online as they will likely change color once introduced into a home system.
In general, an acan coral does best under low to moderate lighting. This gives some freedom for placement, filling in shaded areas of the reef tank and bringing color to the sandbed.
Are They Difficult To Keep?
Overall, the acan coral is considered one of the easiest lps corals to care for and beginner-friendly. Unfortunately, they are not favored by most beginners though.
Acans do not bring exciting movement to the reef tank like other LPS coral like Euphyllia that wave in the water current. On top of this, they do not grow fast and hobbyists might be left wanting more.Many of the cheaper varieties are much less colorful than the more desirable ones, so there is no real incentive to waste space on one of these seemingly boring corals.
However, acans are very hardy and can adapt to most tank conditions. Their low lighting requirements make them a perfect addition for hard-to-fill shaded areas in the aquarium. Once the tank has become established enough, it’s more than worth it to go for the pricier varieties to bring a pop of color to dark areas of the reef tank.
Care And Maintenance
An Acan coral does best in stable conditions with good water quality, unmoved and unbothered. Because these corals are naturally slow-growers, it’s extremely important to keep conditions favorable to prevent delaying the growing process any further.
As a species of LPS coral, the acan coral needs nutrients to build its calcium carbonate skeleton. This includes some nitrates, magnesium, calcium, and trace elements; most importantly, the tank cannot be overly clean, or else your corals will not thrive. Alkalinity also needs to be stable in order for the rest of the system to be stable.
Acan corals do not need any special care and can successfully be kept with sump filtration, a canister filter, or a simple hang on the back filter. A protein skimmer is not necessary and not recommended for low-nutrient systems.
If keeping large colonies of acan coral or keeping SPS coral, it is recommended to dose those nutrients needed. However, acans are eager eaters and can get most of their nutrition through regular feedings.
Though acan corals might not be the most exciting to watch in the reef aquarium, they’re one of the favorites to feed. These corals will accept most foods most of the time. You can tell they are hungry as they release their small, inner clear tentacles; some hobbyists have trained their acan coral colony to show these tentacles at feeding times.
Otherwise, a healthy acan coral should have its feeding tentacles out a majority of the time. If you don’t see yours during the day, check back when the tank lights are shutting off and shortly after. If you still don’t see tentacles, make sure the coral looks healthy otherwise.
Most hobbyists consider feeding acan corals a must for success. Yes, they can sustain themselves with the nutrients available in the water column, but additional feedings really make them thrive. You check out this video by The Reefer for a nice overview on feeding an acan coral.
What Do They Eat?
These corals can be fed a variety of foods and are very willing to try new things. Unlike other LPS coral, acans are relatively quick to eat. Simply place the food in the center of the polyp and the coral will start to eat almost immediately.
This makes feeding easier as you’re not dealing with hungry fish or invertebrates that are trying to steal the food away. Good acan coral food options are fresh or frozen krill, brine shrimp, Mysis shrimp, and bloodworms as well as larger pieces of seafood, like fish, shrimp, and mollusks. Acan corals can also be fed coral powders and pellets, like Reef-Roids.
Some hobbyists like to feed their acans every day, though this can start to cause nutrient buildup from the leftovers. Instead, target feed your acan corals 2-3 times a week. This may be done at night as this is when their tentacles are most present. They really live foods like Reef Roids. Make sure to feed each head.
Feeding your LPS corals will promote good health and growth. Reef Roids is the best in the business for coral food
What Are Good Tankmates?
These corals can be kept with most species of fish and invertebrates. With any reef aquarium system, you want to avoid species that are not reef-safe, like puffers, angels, and triggers. Keep in mind that most crabs are also not reef-safe.
Some better reef safe fish would be:
- Select wrasses
While gobies and blennies are reef-safe, they may choose to use your acan coral as a perch which will cause the coral to retract. Though this doesn’t directly injure the coral, it can interfere with photosynthesis and nutrient intake. It is also very unlikely that the coral will grow or reproduce if it is constantly stressed by a fish or invertebrate walking over it.
Not only do acan corals grow slower than most other LPS coral species, but they can also be more difficult to frag. This is because the skeleton of the colony is connected throughout and can only be separated by an electric saw or a very careful bone cutter.
If using an electric saw, simply cut the coral around the contour of the polyp. Make sure to never cut through the polyp as this will most likely kill it. Attach the frag to a piece of rock or frag plug and make sure to dip it in iodine or another coral solution; acan corals are very susceptible to bacterial infections and a dip will help keep the coral healthy and speed up recovery.
If using a bone cutter, the process is the same. However, you need to be much more careful with where you cut and to make sure you don’t accidentally split the skeleton elsewhere in the colony as this could damage the whole colony. Given how precise you need to be when fragging Acan, I prefer a bandsaw like a Gryphon.
Best For Pro Fraggers
The Gryphon Bandsaw is a high quality commercial fragging tool. Made in the USA and equipped with a diamond band saw. This is used to cut the highest quality, cleanest cuts possible for coral fraggers!
How Fast Do Acan Corals Grow?
It is generally agreed that acan corals grow very slowly, but once they get going, they will quickly fill up space. Be prepared to wait close to a year to see any signs of growth from your acan coral. From there, they can develop several new heads at a time within a couple of weeks.
Why Is Your Coral Dying?
There are a few reasons why your acan coral might be dying. Some of the most common explanations are nutrients, light, other corals, or fish/invertebrates.
- Acan corals need nutrients to survive. For the last decade, hobbyists were convinced that all water parameters needed to be 0 ppm. This starved the corals and left hobbyists wondering what they were doing wrong. Acan corals need these nutrients from the water column to grow. This can then be supplemented with additional feedings. If your coral is lacking in color or not fully extending, test for nutrients.
- Remember, these corals prefer low light conditions. More light is not always better, though this might be true for more advanced LPS corals and SPS species. With acan corals, less light is better for growth and color. If you think your acan coral is too high in the tank and changes color or is retracted, then it probably is. Try slowly moving it to a more shaded area of the reef aquarium. They don’t like being in too much light!
- Acan corals are pretty aggressive corals. They have been known to engage in coral warfare more even aggressive LPS coral and SPS corals and win. However, they lack sweeper tentacles so their defenses are limited. If they are being stung by a coral with longer tentacles, they may be taking damage. Take a look into your tank at night and look for any corals that have their tentacles extended. Move the acan coral if necessary.
- Finally, your acan coral might be dying because it doesn’t get the chance to fully extend without being walked over or picked at by a fish or invertebrate. Observe your tank a few times throughout the day and take a headcount of where everything is. Watch how snails, hermit crabs, urchins, blennies, and gobies move throughout the day.
Acan corals are pretty hardy and are not ones to die overnight without any explanation. Most likely, one of the reasons listed above is why your coral is not thriving.
Make changes, but remember to do them slowly. Too many changes all at once can also damage your acan coral and unbalance your entire system.
Acan corals aren’t the most popular coral, but they’re one of the easiest to care for and funniest to feed. Unfortauntely, they have been designated designer names which can make the more desirable varieties unattainable for some hobbyists. Luckily, the three species, Acanthastrea echinata, Acanthastrea bowerbanki, and Micromussa lordhowensis, give plenty of options. Even the simplest-colored acan coral can bring additional color and life to an otherwise dark and empty space of your tank!
We hope you’ve enjoyed this blog post about Acan coral care. If it’s been inspiring and informative for you, we’d love to hear from you in the comments! What do your favorite coral varieties have that others don’t? Do they require different care or feeding than other species? Let us know below!
Mark is the founder of Aquarium Store Depot. He started in the aquarium hobby at the age of 11 and along the way worked at local fish stores. He has kept freshwater tanks, ponds, and reef tanks for over 25 years. His site was created to share his knowledge and unique teaching style on a larger scale. He has worked on making aquarium and pond keeping approachable. Mark has been featured in two books about aquarium keeping – both best sellers on Amazon. Each year, he continues to help his readers and clients with knowledge, professional builds, and troubleshooting.