Author: Bob Goemans
Common Names: Button coral, meat coral, doughnut coral, cat's eye coral, tooh coral
Phylum: Cnidaria (stony coral)
Range: Tropical Indo-Pacific and the Red Sea
Natural Environment: This mostly circular-in-shape photosynthetic stony coral with a single largy fleshy polyp generally inhabits outer reef slopes and drop-offs where water is sometimes quite turbulent, however without directly affecting this species.
Water Requirements: Calcium 380 to 430 ppm, alkalinity 3.5 meq/l, pH 8.1 to 8.2, specific gravity 1.024 to 1.026, and a temperature range of 74° to 82°F (23° to 27°C).
This is a very hardy, disease-resistant stony coral that's seen quite frequently in the trade. Nevertheless, it appears to be quite sensitive to chemicals released by other corals, and it therefore should be given adequate space so it will not come in contact with other corals—even mushroom corals. As for placement, areas that receive low to moderate light and gentle water movement will suffice, with the polyp always facing upward. Keep in mind this species is not found on soft substrates, so elevate it properly and keep it away from strong currents and bright direct light.
As for feeding, this photosynthetic stony coral will do well without any special feeding, even in moderate light. But it will take meaty foods, such as fortified brine shrimp, mysis, small pieces of marine fish/shrimp flesh, rotifers, and/or products containing cyclops or similar products when its feeding tentacles are displayed. And it will sometimes display them if it senses food entering the aquarium during the daytime. To initiate this, I have used freeze-dried krill squished between my fingertips in the aquarium water. Feeding, in my opinion, should not occur more than once every couple of weeks, as I've seen this coral and others similar to it go through some odd shape changes after feeding, and become abnormal looking thereafter for various lengths of time.
This coral also seems to be a good indicator of water quality. When conditions are excellent, i.e., the water parameters are near those found in the wild, there's far greater polyp expansion than when water parameters become nutrient rich.
Do not remove a specimen with highly inflated tissue from the water, as the weight of the water in the polyp may damage or tear its flesh. Gently shake the specimen and allow the flesh to retract somewhat before removing.