Acropora tortuosa

Acropora tortuosa takes its name from its twisted, tangled branches: long, slender branches rising from a common base bend in different directions to form an open, sparse bush. In the hobby it is simply called a "tort". Brown and cream colonies also exist, but the forms that draw real interest in the hobby come in striking blue, purple and lavender tones.

Because its branches are thin, it is fragile and forgives husbandry mistakes less than most Acropora species. It succeeds in aquariums that are at least a year old, with stable KH and well-established filtration; it is not suitable as a first stony coral.

Trade in stony corals is subject to CITES Appendix II. The famous tort clones have been propagated in aquariums for years; choose a frag or a farmed colony.

• Oregon Tort: With its bright blue-purple color, the hobby's most famous tort clone; it is said to have been propagated from a single colony.
• Cali Tort: Together with the Oregon Tort, one of the oldest and best-known tort clones in the hobby.
• Other named torts: Also sold under other names given by vendors; all are color forms of the same species.

It lives in the Indo-Pacific, especially in the lagoons and on the sheltered reef slopes of Western and Central Pacific islands; some of the hobby's famous clones came from the Solomon and Marshall Islands. Here the light is strong and the flow steady, but wave impact is low; thin branches can only grow long in sheltered places like these.

• Light: High light; roughly 250–400 PAR. Blue forms turn brownish under low light and bleach at the tips under excessive light. A new frag should be acclimated to the light over three to four weeks.
• Flow: Strong, random flow; the branches should sway slightly. A constant, harsh pump outlet breaks thin branches.
• Placement: The upper part of the rockwork, with plenty of open space to grow upward and outward. Leave 10–15 cm between it and its neighbors.
• Water parameters: Salinity 1.025–1.026, temperature 25–26.5°C. KH 7–9 dKH with daily swings below 0.5 dKH; calcium 400–450 mg/L; magnesium 1300–1400 mg/L. Nitrate 2–10 mg/L, phosphate 0.02–0.08 mg/L.

Most of its nutrition comes from light and the zooxanthellae algae in its tissue. Occasional very fine powdered food, rotifers or amino acid supplements can help color and growth. Adjust the amount of feeding according to your nitrate and phosphate readings.

It is not aggressive, but its thin branches are very vulnerable to the tentacles and chemicals of neighboring corals. Keep it away from LPS, soft corals and spreading Montipora.

Dwarf angelfish may pick at the polyps. Acropora-eating flatworms (AEFW) and red bugs are the greatest danger for this species too; put newly arrived pieces through a coral dip. Large hermit crabs and large snails roaming the tank can break the thin branches.

Branch tips 3–4 cm long are cut and attached to a frag plug with gel glue. Because the branches are thin, the cut must be clean and the piece must not be crushed. After cutting, the frag is placed somewhere with good flow and light similar to the mother colony. Thinning the colony by cutting branches that grow inward gives the remaining branches more light and flow.

• Rapid tissue necrosis (RTN): A colony can be lost within days after a sudden change in KH, temperature or salinity. Immediately cut healthy branch tips and save them as separate frags.
• Slow tissue necrosis (STN): Tissue recedes upward from the base; depleted nutrients and weak flow are common causes.
• Color loss: Blue tones turning brown point to a lack of light or high nutrients.
• Pests: Crescent-shaped bite marks indicate AEFW; tiny dots scurrying over the tissue indicate red bugs.