Algae guide
Black Beard Algae (BBA): What Causes It and How to Remove It
Last updated: May 2026
- What it is: A tough red-alga filament (popularly called Black Beard Algae) that grips plant leaves, décor and edges of hardscape.
- Severity: 3 / 4 - Moderate - smothers leaves and slows growth; manageable with repetition
- Primary cause: Unstable dissolved CO2 swings and drifting carbon availability are recurring triggers alongside organic loading that lets periphyton communities shift.
- Primary fix: Stabilise gas injection or liquid carbon dosing rhythm, mechanically remove softened tufts under water, spot-treat only where labelled safe.
Looks & where it settles
Initially wispy sooty strands maturing into bushy charcoal tufts anchored along leaf margins, moss fronds and filter outflows.
Why it thrives
Carbon availability that swings day to day stresses higher plants more than rugged algae prototypes; combined with hotspots of debris and stalled flow tufts consolidate.
See also our water parameters overview and why cycling fundamentals matter for algae competition.
Risk for fish
Mechanical nuisance for plants and aesthetics; livestock rarely harmed unless chemical overdosing burns tissue - always dose conservatively outside livestock splash zones.
Treatment stack
Manual: Trim heavily infested foliage, uproot fluff from hardscape gently so fragments drift into filter floss rather than resetting elsewhere.
Chemical spotlight: Hydrogen-peroxide dips or targeted pipette dosing turn healthy filaments ivory-pink confirming Rhodophyta identity - observe livestock reaction and stop at first stress.
Excel-style liquid carbon: Spot dosing per manufacturer aquarium guidance suppresses stubborn tufts; repeat sparingly alongside large water refresh.
Biological: True Crossocheilus oblongus / siamensis hybrids remain the lone widely trusted fish grazers yet mislabelling floods trade - buy from reputable breeders only.
Before changing fish load, sanity-check biomass with our free aquarium stocking calculator.
Long-term prevention
Ride one consistent CO2 curve per photoperiod, declutter stagnant corners, rinse detritus from moss regularly and keep phosphate/nitrate from bottoming out - starved macros invite odd biofilms.
Recovery timeline
Expect several partial assault cycles across a few tank maintenance weeks; plant leaves already skeletonised seldom recover pigment - replace them instead of hoping bleach-white tissue greens up.
Track your tank health and diagnose problems with App-aquatic.
Get App-aquatic → Free stocking calculator →