Species Catalogue

Fine, fluffy dark green tufts that resemble a softer version of Bryopsis. Often appears in high-nutrient systems and around powerhead intakes. Like Bryopsis it is resistant to most herbivores. Sea hares will consume it; magnesium treatment (1500–1800 ppm) is effective. Reducing phosphate below 0.05 ppm also helps.

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.

Flat, iridescent brown-olive blades that spread over rockwork and corals. Beautiful under certain lighting — shimmers blue-green — but highly invasive in reef tanks. Produces chemical deterrents that most fish avoid. Very difficult to eliminate; manual removal stimulates regrowth. Sea urchins (Diadema) and Thalassoma wrasses occasionally graze it.

Brown, stringy, bubble-filled slime that often appears in new reef tanks — frequently mistaken for cyanobacteria. Dinoflagellates ('dinos') form slimy mats that can smother corals and sandbed. Treatment is complex: raise nitrates (>2 ppm), raise phosphates (>0.05 ppm), run extended dark periods, and increase UV sterilisation. One of the most frustrating reef nuisances.

Brilliant scarlet-red, blade-shaped macroalgae — one of the most visually striking species for display refugia. Provides excellent colour contrast and nutrient export. More delicate than Chaeto; requires moderate flow and consistent light. Popular with collectors and stunning under reef lighting.