When I started in the hobby in 2008, there was a legitimate problem with dyed corals and anemones. Sadly, this was not a new problem at that time either. Bleached corals (or even healthy corals) were subjected to dye baths in a dizzying variety of colors, especially in rare shades, such as yellow and blue. Unfortunately, that practice had unsurprisingly deleterious effects on the animals, as the dye interfered with their photosynthesis via zooxanthallae. Fast forward over a decade, and the frequency of dyed corals showing up in local fish stores for sale substantially decreased. So, imagine my shock when a fellow reefkeeper sent me a message about a potentially dyed blue sun coral. The earliest reporting of blue sun corals in the hobby I could find dated back to 2017.
Panic Hits – Artificially Dyed Corals in a Pandemic:
In June 2020, right in the middle of a global pandemic, I was appalled to see reports popping up all over multiple reefkeeping forums and other social media sites claiming that there was a sudden influx of dyed corals. Rehabilitating dyed corals is no picnic; it takes daily feedings, lots of carbon to absorb any free dye, and fast removal of necrotic tissue. Even then, I have never had success with them long-term. Panic started to hit me, as my aquariums were severely neglected thanks to trying to telework and homeschool young children simultaneously. Not only were my tanks ill-prepared, but I couldn’t get the supplies necessary for rehabilitating dying coral. Chlorine bleach and hydrogen peroxide are two of my main staples to keep clean equipment, and they were nonexistent on shelves at the time.
Assessing Blue Sun Coral Health:
Then, on 8 July 2020, a fellow local reefkeeper posted on Facebook that she had just received one of these (on 18 June) and suspected it was dyed and dying. She was concerned that it was affecting her yellow sun coral too, as it seemed to be losing color. So, it was time for me to do some research!
Although I had a lot of questions, my first question was on how to stabilize the coral. Since the owner believed it was dyed, I needed to determine what dyes could have been used so I could figure out how to remove it. Sun corals are often various shades of orange or yellow, so the idea of getting a solid blue coral seemed a bit crazy to me. In other words, I thought that just adding blue dye to a yellow coral would likely result in a greenish coral. However, I’ve used methylene blue extensively, and I know its staining power! It seemed a plausible dye to overcome the yellow.
While researching the various dyes, I found research suggesting that anemones could safely tolerate methylene blue dye, as it did not affect the anemones’ growth or survival. Additionally, the research found that the anemones only retained the methylene blue for approximately six weeks. This gave me hope. Maybe the sun coral was dyed with methylene blue, so it might live if I could feed it adequately (as a non-photosynthetic coral, there is no zooxanthellae interference). I was also prepared with activated carbon to absorb any leaching dye (although this research on using dragonfruit skin was super interesting!)
Bringing the Coral Home:
Only three days later, on 11 July, we met in a mall parking lot, while wearing masks and maintaining social distancing. Even in the hot mid-day sun, the coral was a shocking blue color. I quickly took both the blue and yellow corals home. I followed my standard coral assessment procedure, and several things concerned me.
Determining the Coral’s Condition:
First, I’ve never previously had my hands or equipment get any sort of coloration on them while fragging. Was this the “dye?” I could see blue, yellow, and green colors on this while towel.
Second, the yellow sun coral had a case of “brown jelly disease” starting. This was not good.
Although the tissue appeared dyed, the skeleton of the coral was white as usual. This was not what I expected, especially if the coral was submerged in dye. However, the anemone research referenced above suggests a dye method that may work on just the tissues. At this point, I wasn’t convinced either way on if it was dyed.
Quarantining the Blue Sun Coral:
After initial treatments, I placed the corals into my quarantine tank for observation. I started them on small pellet food, as sometimes that seems easy for corals to digest. Once the coral was regularly eating, I switched it to a varied diet of Roti-Feast, Oyster-Feast, Phyto-Feast, Reef-Roids, and baby mysis shrimp.
Unfortunately, the “brown jelly” spread to my other corals in quarantine, but I was able to keep it from progressing on the yellow sun coral or to the blue sun coral.
About a week after arrival, I was once again convinced that this coral was dyed, as the healing fragmented portion was a dark greenish-yellow. Ah ha!
But this coral decided to just keep me guessing. Wouldn’t the tentacles be blue as well if it was dyed?
Blue Sun Coral Grow-out:
By a month after arrival, I was sure it was natural, as it was just becoming more blue with bright yellowish green polyps. How was that possible?! Methylene blue should’ve mostly dissipated by that point. It had to be natural, right??
Oh but wait… This coral just wants to keep us on the edge of our seats! After four months in my tank, the shadowed areas were turning yellowish green! But, notice the baby polyp – it’s blue! My head was starting to hurt. (And yes, unfortunately I was not feeding the coral as much as necessary, so it was receding. My tanks were quite neglected during COVID-19, as you’ll see by the algae and aiptasia.)
In reviewing the 2017 post photo, the shaded regions display similar coloration.
Spawning of the Blue Sun Coral!
On 12 December 2020, five months after getting the coral, I woke up to find this blue sun coral spawning! And, the planulae were orange (not blue) – suggesting the coloration was natural (and reproduction hopefully not affected).
One of the planulae immediately settled onto the glass, where I watched it eagerly (until it disappeared about three days later).
Here are some of the planulae. Unfortunately, none of them survived, or maybe they weren’t even fertilized in the first place.
According to username, “Tennyson,” on Nano-Reef, the dark orange/ brown ones are “duds” while the more yellowish planulae are viable (assuming this is consistent across all sun coral colorations).
(For more reading on sun coral reproduction, please see the references below.)
Although the tank wasn’t exactly clean, both sun corals were appreciating the high nutrient levels!
Final Thoughts:
Although I took this photo under actinic lighting, the blue of the sun coral is very similar to the blue of the Oregon Blue Tort Acropora coral. This amazes me as one is photosynthetic while the other is not. In advertising the Oregon Blue Tort, there are plenty of websites that describe the blue as “so vivid it makes you wonder whether it was injected with an artificial blue pigment,” “often considered the bluest Acropora coral you can buy,” “one of the bluest of the blues,” and “so blue it almost looks fake.” I can see why this blue sun coral was also believed to be dyed!
Conclusion:
Over 13 months later, here it is (under actinics again, so the yellowish green polyps are hard to capture on the camera). I lost four polyps, and a few polyps shrank but are now re-growing. The coloration hasn’t changed a bit. The tissue is brilliant blue, the tentacles are yellowish-green, the oral cavity is yellowish-green, and the center of the polyp is blue. Shaded areas turn yellowish-green, but they regain the brilliant blue color once exposed to light again. This makes me believe it’s a structural blue versus a pigment.
Although I lost four polyps, this gives me an opportunity to clean the skeleton to help identify the coral (to be included at a future point). I am convinced that this coral is not dyed, but I have no explanation for its coloration, especially as blue is rare in nature.
So, let’s celebrate this amazing coral with a happy ending. It was fate that on 25 July 2021, the Washington D.C. Area Marine Aquarist Society (WAMAS) hosted a virtual meeting with guest speaker, Matt Wandell, from the Monterey Bay Aquarium. His topic was on “Use and Care of NPS Corals.” Of course, I had to chat with him about this unusual beauty. I am happy to report that we have made arrangements for at least half of the coral to go on display at the Monterey Bay Aquarium in the fall of 2021 (once the weather cools down).
References:
Arthur Jen, 2017 (original post is now deleted). https://www.reef2reef.com/threads/baby-jb-for-trade-southern-california.333673/
BSA Corals, “Blue Emerald Sun Coral!,” 26 June 2020. https://www.reef2reef.com/threads/blue-emerald-sun-coral.733669/
Calfo, Anthony, “The Tragedy of Artificially Dyed Live Corals,” September 2002. http://www.reefkeeping.com/issues/2002-09/ac/feature/index.php
Fatheree, James, “Aquarium Corals: A Look at the Sun Corals,” Advanced Aquarist, 2011. https://reefs.com/magazine/aquarium-corals-a-look-at-the-sun-corals/
Mizrahi, D., Navarrete, S. A., and Flores, A. A. V., “Groups travel further: pelagic metamorphosis and polyp clustering allow higher dispersal potential in sun coral propagules”, Coral Reefs, vol. 33, no. 2, pp. 443–448, 2014. https://core.ac.uk/download/pdf/37522324.pdf
ReefdUp, “Blue Sun Coral Spawning!” 12 December 2020. https://wamas.org/forums/topic/95817-blue-sun-coral-spawning/?_fromLogin=1
Rowlett, Joe, “A Field Guide to Sun Corals,” 2015. https://reefs.com/magazine/field-guide-sun-corals/
Tennyson, “How to tell if a coral is dyed a different color?” 6 July 2020. https://www.reef2reef.com/threads/how-to-tell-if-a-coral-is-dyed-a-different-color.736716/
Tennyson, “HUGE Sun Coral Spawning event,” 9 October 2019. https://www.reef2reef.com/threads/huge-sun-coral-spawning-event.654328/
Wells, CD, Sebens, KP, “Individual marking of soft-bodied subtidal invertebrates in situ – A novel staining technique applied to the giant plumose anemone Metridium farcimen (Tilesius, 1809),” PLOS ONE 12(11): e0188263, 21 November 2017. https://doi.org/10.1371/journal.pone.0188263