The short answer
Very few animals eat black beard algae — the tough, dark tufts that grow on leaf edges, hardscape and equipment. The main grazers are the Siamese algae eater and, to a lesser extent, Amano shrimp. But black beard algae is a CO2-and-flow problem, so no fish will cure it alone. The lasting fix is stable CO2, good water flow, and spot-treating the tufts with liquid carbon, with algae eaters as backup.
The animals that will graze it
Black beard algae is tough and most clean-up crews ignore it, but a couple of species help:
- Siamese algae eater — the standout choice; one of the only fish that reliably eats black beard algae, especially younger growth when kept a little hungry.
- Amano shrimp — will pick at softer, newer tufts, though they won’t clear a heavy infestation.
Treat both as helpers that keep regrowth down — not as a fix for the outbreak itself.
The real fix: CO2, flow and spot-treatment
Black beard algae takes hold when CO2 is unstable and flow is poor, so that’s what you address:
- Stabilise CO2. Keep injection steady through the photoperiod rather than swinging. Browse CO2 systems.
- Improve flow. Angle the filter output or add a circulation pump so no dead spots let algae settle. Clean a clogged filter.
- Spot-treat. With the filter off for a few minutes, dose liquid carbon directly onto the tufts. They turn red and die back over several days, then can be removed.
Keep it away
Once cleared, hold CO2 steady, keep flow strong into every corner, run a 6–8 hour photoperiod on a timer, and do weekly water changes. For the full background see what black beard algae is and our how to get rid of aquarium algae guide.