Flora & Fauna

Fast-growing macroalgae with flat, oval blades on creeping runners. Excellent nutrient export and refugium algae. Can go 'sexual' under stress — turning milky white and releasing gametes, causing a tank crash. Keep under 24h light or harvest regularly to prevent this. Widely available and very effective.

The most popular refugium algae in the reef hobby — tumbling masses of stiff, wire-like bright green strands. Grows rapidly, exporting nitrates and phosphates as it's harvested. Provides a habitat for copepods and amphipods that migrate into the display tank as live food. Extremely hardy.

Brown, dusty coating on glass, substrate, and decorations — the most common algae in newly set-up tanks. Feeds on silicates from tap water and substrate. Almost always disappears on its own within 6–8 weeks once silicates are depleted. Otocinclus catfish and nerites clean it rapidly.

Feathery, fern-like fronds on creeping runners — arguably the most attractive Caulerpa species. Works well in display refugia where its ornamental appearance is on show. Fast-growing nutrient exporter. Same caveats as other Caulerpa: harvest regularly to prevent sexual reproduction.

Short, fuzzy green tufts — typically 2–5 mm — that appear on the edges of plant leaves, hardscape, and equipment. One of the most common algae in newly planted tanks. Easily grazed by Amano shrimp, Otocinclus, and nerite snails. Caused by light excess or inconsistent CO₂ early in a tank's life. Usually resolves as the tank matures.

Creeping runners bearing upright branches tipped with small spherical beads — resembling tiny bunches of grapes. One of the most vigorous nutrient-exporting macroalgae; grows rapidly in refugia. Can go sexual and crash if left unharvested for too long. Listed as invasive in the Mediterranean.

Attractive calcified green macroalgae with segmented, coin-like lobes. Grows upright and anchors into sandbed or live rock. Naturally calcified — contributes to calcium demand. Fish tend to leave it alone. Adds a natural look to the display tank and provides nutrient export.

Wiry, reddish-brown branching macroalgae that tangs and rabbitfish readily consume. Grows quickly and provides excellent nutrient export in refugia. Attaches loosely to rubble and rock. One of the most palatable macroalgae for herbivorous reef fish — can be offered directly as live food.

Feathery, pinkish-white tufts of jointed calcified branches — a beautiful encrusting coralline relative that forms soft mats on rockwork. Provides habitat for tiny amphipods and copepods. A common and welcome hitchhiker on Mediterranean and Atlantic live rock. Tolerates cooler water than most corallines.

Beloved velvety-green spheres of filamentous green algae — not a moss at all. Forms naturally in cold lakes where wave action rolls colonies into balls over decades. A low-maintenance aquarium icon that grows extremely slowly. Rotate occasionally for even light exposure.

Bushy red-to-burgundy macroalgae prized as live food for herbivorous fish — tangs, rabbitfish, and urchins graze on it enthusiastically. Also an excellent nutrient exporter in refugia. Tumbles well under flow and tolerates a wide range of conditions.

Bright green, tissue-thin sheets of macroalgae familiar on coastlines worldwide. Fast-growing nutrient exporter and a relished food for tangs, urchins, and rabbitfish. Tolerates a very wide temperature and salinity range. Can become weedy if not harvested — keep export-focused.

Bright green filamentous algae with distinctive spiral chloroplasts. In small amounts it's a natural part of the ecosystem and a food source for many invertebrates. Can quickly overtake a tank if nutrients or CO₂ are out of balance. Best controlled by reducing phosphates and manual removal.