Genus Tubastraea - Sun Corals
A Great Coral with an Undeserved Poor Reputation
When Eric Borneman wrote Aquarium Corals back in 2001, he called sun corals (Tubastraea spp.) “one of the most widely recognized corals in the world,” pointing out that “[a]lmost all coffee table books on coral reefs have a picture of these beautiful corals.” If that isn’t a ringing endorsement for these gorgeous animals, then we don’t know what is. Unfortunately, too many aquarists acquire one of these animals without fully understanding its husbandry requirements, and the result, more often than not, is a slow decline in health and the eventual death of the specimen. Keeping sun corals from the genus Tubastraea need not be difficult, however, so long as the aquarist is informed and conscientious.
Leading Cause of Aquarium Tubastraea Mortality
The number one reason why sun corals die in the aquarium is starvation. These animals are not photosynthetic as many popular aquarium corals are. In other words, the aquarist cannot rely on reef-ready lighting supporting healthy zooxanthellae populations which, in turn, will sustain the coral. Instead, this non-photosynthetic coral must be target fed in captivity if it is to survive. The conscientious aquarist will understand this and regularly target feed the coral with planktonic food such as mysid shrimp, adult brine shrimp, Cyclopeeze, or oyster eggs.
Training a New Sun Coral to Feed
A well-acclimated Tubastraea spp. will readily accept target feedings, although a newly acquired specimen may need to first be trained to accept a captive diet. To do this, wait for the lights to go out and then deliver the food with a turkey baster adjacent to the coral so that the current will carry the food over the closed polyps. If the current is too strong, and there is no feeding response to the broadcast food, then consider turning off the powerheads and allowing some food to land on the coral itself. In time, the patient aquarist should be rewarded by extended polyps at night. Most specimens can then easily be trained to also open their polyps during the day as well.
In terms of water movement, these corals like moderate to high flow, as they rely on this flow to bring them food. In the wild, it is common to see Tubastraea species in high flow situations. Be sure not to tuck one of these corals deep in a cave thinking it will flourish in the low light setting. Too often these dark locations have low flow, and while Tubastraea species can tolerate bright light, they will rarely do well with low flow.
When it comes to light, it is true that Tubastraea species are non-photosynthetic corals, but, so long as they are properly light-acclimated, these animals can tolerate relatively bright reef-ready lights. In fact, some of these corals grow in direct sunlight in the wild.
It is unfortunate that Tubastraea species have gotten somewhat of a poor reputation in the marine aquarium hobby, as they truly are one of the more beautiful, readily-available corals. As explained above, the bad reputation has much to do with the perception that these corals don’t survive in the aquarium, but this supposition is almost entirely based on animals which have not had their nutritional needs met. The responsible aquarist who takes the time to appropriately feed his or her Tubastraea species should be rewarded with a healthy coral that will readily reproduce in the aquarium.