Bubble corals (Plerogyra sinuosa) are very distinctive large polyped stony (LPS) corals that are relatively easy-to-keep in reef aquariums.
By day, the bubble coral skeleton is protected by fully inflated white, cream or light green bubbles that look alien frogspawn. At night the bubbles retract and the coral extends sweeper tentacles to fight for space and hunt for food.
These sweeper tentacles will sting and kill rival corals, so give your bubble coral plenty of space; up to 12-inches may be required. Watch nearby corals for any signs of warfare.
When purchasing a bubble coral, look out for tears in the bubble tissue due to rough handling. Such a coral may not survive. Otherwise bubble corals are fairly hardy once established in a good reef aquarium.
Positioning your bubble coral in the tank
Bubble corals usually come from deeper areas of the reef, which means they don’t need very intense lighting. In fact, some speculate the bubbles are a way of reducing light intensity. Moderately lit areas to the side and bottom of a typical reef tank will provide sufficiently lighting for photosynthesis with bubble corals.
Some say that if the coral is darker in colour it may come from a deeper area of the reef, while lighter ones may be used to more light. Be prepared to move the coral if it’s not thriving, but don’t rush things.
Like many LPS corals a slow gentle water current definitely suits Plerogyra best – think lagoon zone, rather than reef crest. Too much water movement may prove damaging.
The standard high-quality reef tank water conditions are required for bubble corals. Not to the extreme low nutrient extent demanded by small-polyped corals – LPS are typically a halfway house towards soft corals in this regard – but well-oxygenated water of the appropriate temperature, salinity, pH and carbonate hardness is a must.
Be aware that some fish, especially angelfish, will pick at a bubble coral to such an extent they kill it. Smaller reef fish are no problem.
Feeding bubble corals
The real secret of success with bubble corals, as with other LPS, is feeding. Feed lightly with small pea-sized bits of fresh fish or a smattering of defrosted frozen mysid shrimp once a week (feed the fish first to stimulate the tentacles for feeding). Don’t overfeed, or you may overwhelm the coral.
Bubble coral time feeding: time-lapse video
Propagating bubble corals
The big downside with bubble corals is the difficulty in propagating them. Like a lot of LPS, fragmentation is possible but a slow process. Sometimes adults will produce small buds along the base of the colony, which can be snipped off and moved elsewhere.
Few aquaculturists offer captive-breed bubble corals, though, which make reef-acquired specimens the norm. Small colonies may be collected whole, or snapped off branches of larger colonies. Bubble corals are fairly common in the wild, but I always prefer to buy captive-bred or aquacultured corals where possible so I’d love to see more captive propagation, perhaps by larval settlement.
- Read more on propagation of LPS corals at Reefkeeping magazine
Read the Ultimate Secrets To Saltwater Fish And Invertebrates.
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