Acropora carduus

Acropora carduus is an open-branching, thin-branched Acropora with the smooth skin typical of deepwater species. Its branches stay relatively slender and widely spaced compared with dense corymbose forms, giving a clean, airy colony. In aquaculture it appears in red and pink, blue, and green colour forms, with colour often soft at the base and stronger toward the tips when the coral is settled.

Care

This is an advanced deepwater Acropora best kept in a mature, stable SPS system. Alkalinity stability comes above all else — hold a steady daily value rather than correcting in bursts — and keep calcium and magnesium consistent alongside it. Provide high, strong random flow that washes across the thin branches from changing directions; never aim a constant jet directly at the colony. As a medium to high light deepwater species, it does well around PAR 150–300, acclimated gradually and watched for paling if intensity rises too fast. Look for an encrusting base spreading at the mount and regular polyp extension as signs of health.

Placement and growth

Place Acropora carduus at the top of the aquascape in this care profile, but favour a spot with strong flow and not the single most intense point of light in the tank. Keep at least 2 in of minimum clearance from neighbouring corals so its open branches receive light and flow on all sides. Growth is moderate once based down; a colony that encrusts first and then extends upward is progressing normally for this species.