Knob Coral

About

Knob Coral (Dipsastraea rosaria) is a large-polyp stony coral that turns up across a wide range of Indo-Pacific and broader tropical reef systems, which gives you a clue about how adaptable it can be in a well-run reef tank. The surface is defined by distinct, rounded corallites arranged in a plocoid pattern, each polyp sitting in its own individual wall rather than sharing boundaries with neighbors, giving the colony a bumpy, textured appearance that stands out against smoother encrusting neighbors. Coloration tends toward earthy greens, browns, and muted golds, occasionally with contrasting oral disc tones, though color can shift depending on the lighting and zooxanthellae density in any given system. In the wild, colonies form rounded domes or broad plates and are a reliable presence on shallow to mid-depth reef structures. In the aquarium, Dipsastraea rosaria sits comfortably in the intermediate category. It rewards consistent water quality and stable conditions but is not as fussy as some of the more demanding LPS corals. Moderate lighting and moderate flow suit it well. Give it enough space from neighbors since it can extend sweeper tentacles at night to defend its territory, which is worth keeping in mind when placing it in a mixed reef.