Acanthophora

Acanthophora · also called Purple Prickly Seaweed, Pink Prickly Seaweed, Prickly Seaweed

Acanthophora is a stiff, prickly red macroalgae with branching growth in reddish purple to reddish orange. Its brittle branches snap easily, and broken pieces can grow into new plants. A. spicifera is the most widespread alien seaweed in Hawaii, so it must never be released, and it can spread in a tank.

Educational only. Some KinStation entries are reviewed by licensed veterinarians, but none can replace an in-person exam. Always consult a licensed veterinarian or board-certified specialist for diagnosis, treatment, or any decision affecting your pet's health.

Quick facts

Category	Marine & Algae
Family	Rhodomelaceae
Native origin	Tropical and subtropical seas; A. spicifera is invasive in Hawaii
Care difficulty	Intermediate
Light	Medium light
Pet toxicity	Toxicity unknown

Light

Moderate reef lighting is a sensible start, and no firm figures are recorded for tanks. In the wild it is abundant on shallow reefs, so it may grow faster under brighter lamps. If you want to limit its spread, avoid giving it the strongest light in the system.

Water

Standard reef parameters: 23-27 C (74-80 F), salinity ~1.025 SG, pH 8.1-8.4. Nutrient control is the main way to hold it back if it starts to spread. Keep nitrate and phosphate measurable but not high, and prune regularly in any tank that also holds corals.

Soil & potting

Grows on rock and other hard surfaces, and it can also live free-floating once pieces break away. Tie a piece to rubble with line, or keep it loose in a refugium. Handle it gently, because the branches are brittle and shed fragments that can settle around the tank.

Environment — humidity, temperature, placement

Moderate flow suits it in a refugium or macroalgae tank at standard reef temperature, 23-27 C (74-80 F). A contained system is the safest home, because broken pieces travel easily. Never rinse trimmings or pour tank water where they can reach the sea.

Propagation

Spreads by fragments and by spores, and a new plant can grow from the smallest tissue remnant. Keepers only need to snap off a piece and tie it to rubble. The same brittleness makes it hard to contain, so lift out every trimmed scrap and prune before it reaches nearby corals.

Toxicity detail

No toxicity data for tank animals was found, so the rating stays unknown. The main risk is spread rather than chemistry: it is an invasive reef alga in Hawaii and could crowd slower plants in a tank. No grazing deterrent is recorded. Bag and bin trimmings, and never release them.

Varieties & cultivars

Natural forms are the wild species; cultivars are selectively-bred colour or variegation forms of the same plant.

Natural forms2

Purple Prickly Seaweed

Acanthophora spicifera. A reddish-purple, branching alga with a stiff, prickly texture. Its branches are somewhat brittle.

Handle it gently, as the branches snap easily and it is somewhat fragile when moved. Invasive in Hawaii and quick to spread from fragments, so bag and bin trimmings, and never release it or tank water.

Pink Prickly Seaweed

Acanthophora sp. A reddish-orange Acanthophora with a stiff, prickly texture and branching growth. The branches are somewhat brittle.

Handle it gently, as the branches snap easily and it is somewhat fragile when moved. Its relative A. spicifera is invasive in Hawaii and quick to spread from fragments, so bag and bin trimmings, and never release it or tank water.