Green Algae
Hair Algae
Often Oedogonium spp. in aquarium use
Dense coats of green filaments that grow over plants and hardscape and can smother leaves if ignored.
Quick facts
- Category
- Green Algae
- Organism group
- Green Algae
- Growth form
- Filament
- Primary color
- Green
- Secondary color
- Bright Green
- Attachment
- Moderate
- Removal difficulty
- Moderate
Identification
A carpet or coat of many packed green hairs, from short bristles to longer soft hair-like filaments.
- Growth form: Filament
- Primary color: Green
- Secondary color: Bright Green
Looks like: Different from fuzz algae because hair algae forms denser coats instead of isolated short filaments.
Where it appears
Typical affected areas
- On Plants
- On Hardscape
Common contexts
- New Tank
- Too Much Light
- Nutrient Imbalance
Causes
Common when young tanks or stressed planted tanks receive more light than the plants can process.
Most common triggers
- Cycling Phase Instability
- CO2 Or Nutrient Deficiency
- Excess Light Relative To Plant Uptake
Root cause note: Hair algae is a practical hobby label and can include multiple similar green filament types.
Nutrient relevance
Balance relevance: High
Related nutrient issues
- CO2 Deficiency
- Macronutrient Imbalance
- Nitrogen Deficiency Can Contribute
Hair algae often reflects weak plant metabolism rather than one simple overfertilization problem.
Correction hint: Support stable plant growth first, then reduce light if the tank is still overdriven.
Treatment
Quick action: Trim the worst-covered leaves and remove as much filament mass as possible by hand.
Manual removal, better plant growth, and controlled light pressure usually give the best results.
Manual removal: Use fingers or a toothbrush on hardscape; heavily covered leaves are often better pruned.
Difficulty: Moderate
Prevention
Strong plant mass, balanced nutrients, and sensible photoperiods reduce recurring outbreaks.
This page is designed to help with visual identification first, then causes, treatment, and prevention. Actual algae pressure can vary depending on maintenance, livestock, plant mass, light, flow, and nutrient consistency.