Flora & Fauna

Dense, dark grey-to-black tufts that cling stubbornly to plants, hardscape, and equipment. One of the most frustrating nuisance algaes for planted tank keepers. Caused by CO₂ fluctuation and low or inconsistent carbon dioxide levels. Spot-treat with liquid carbon (Excel) or hydrogen peroxide.

Dense, rough-textured mats of dark green filaments that blanket pond plants and surfaces. Common in outdoor ponds and highly nutrient-rich tanks. More coarse and branched than soft hair algae. Difficult to eradicate fully — physically remove as much as possible before treating with algaecide or reducing nutrients aggressively.

A blue-green or red-brown slime that coats the substrate, plants, and glass with a slimy, foul-smelling mat. Technically a bacterium, not true algae. Caused by low nitrates, poor flow, and organic waste. Responds to a 3-day blackout combined with the antibiotic erythromycin or hydrogen peroxide treatment.

Not a true alga but a charophyte — an evolutionary stepping stone between algae and land plants. Whorled branches on brittle stems; produces a distinctive musky smell when crushed. Tolerates very hard, alkaline water that many plants cannot. Often kept deliberately in biotope setups for its unique look.

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.

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.

Fine, powdery green coating on the glass that wipes off easily but returns quickly. Different from Green Spot Algae — much softer and more responsive to physical removal. A large clean-up crew (nerites, Mystery snails, Otocinclus) keeps it in check. Usually a sign of moderate light excess.

Hard, dark green circles on glass and slow-growing plant leaves — familiar to virtually every planted tank keeper. Caused by low phosphate (counterintuitively) and high light. Nerite snails are the most effective control. A small amount is considered normal and harmless.

Pea-soup green tank water caused by a bloom of free-floating unicellular algae. Usually triggered by a combination of high nutrients and direct sunlight. A UV steriliser will clear it within days. A 3-day blackout is an alternative. Daphnia (water fleas) can be added to a fishless tank as biological control.

Fine, bright-green strands that drape over plants and hardscape. One of the most common new-tank algae — usually caused by excess light, nutrient imbalance, or lack of fast-growing plants competing for nutrients. Nerite snails, Amano shrimp, and Florida Flagfish make short work of it.

Dark, wiry filaments of cyanobacteria that form dense mats — often mistaken for BBA. Unlike true algae, it can fix atmospheric nitrogen, meaning low nitrogen levels do not suppress it. Produces toxins harmful to invertebrates. Requires the same treatment as blue-green algae: blackout, H₂O₂ treatment, and improved flow.

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.

Thin, cotton-like green threads that form loose, easily detached clumps — often confused with hair algae but coarser and more tangled. Tends to form clumps rather than sheets. Usually caused by excess ammonia or organics in new tanks. Amano shrimp and Florida Flagfish handle it well.

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.

Grey-green single strands that branch into antler-like forks — often tangled in plant leaves and filter intakes. Like BBA, it signals CO₂ problems. More responsive to spot-treatment with liquid carbon than BBA. Siamese Algae Eaters will consume it.

Very fine, dark green threads — slightly stiffer than Spirogyra and less silky. Wraps tightly around plant stems and mosses. Caused by low CO₂ and high light. Siamese Algae Eaters are one of the few fish that readily consume it.

Remarkable bright green net-like colonies — a tessellated honeycomb of cells visible to the naked eye. Beautiful under a microscope but a serious nuisance in garden ponds. Thrives in warm, nutrient-rich water. Manual removal is the primary method as few animals eat it effectively.