Species data
🔴 Cyanobacteria (Red Slime Algae)
Scientific Name: Cyanobacteria sp.
Common Name: Red Slime, Cyano
Appearance: Slimy red, maroon, purple, or dark green mat; often forms bubbles
Reef Safe: ❌ Harmful to coral and aesthetic
Temperament: Aggressive smothering growth
Diet: Photosynthetic – fueled by nutrients and light
Tank Role: Unwanted pest – blocks flow, smothers surfaces
Description
🔍 Description:
Cyanobacteria, often called “red slime,” is not actually an algae, but a photosynthetic bacteria that can form thick, slimy mats across your sandbed, rocks, and even coral tissue. It’s commonly seen in tanks with excess nutrients, low flow, or imbalanced lighting, and can spread quickly if not addressed.
Cyano traps detritus, blocks light, and reduces oxygen at night, making it dangerous to both coral and fish if left unchecked. It’s often mistaken for harmless film algae at first but quickly reveals itself by its rapid growth and bubble formation.
Why it Appears
✅ Why Cyano Happens:
High Nutrients: Elevated nitrates or phosphates
Low Flow Areas: Allows buildup of waste and detritus
Imbalanced Lighting: Especially high red spectrum or old bulbs
New Tank Instability: Common in tanks under 6 months
Best Predator
🧽 Best Clean-Up Crew for Cyano Support:
Nassarius Snails – stir the sandbed and consume waste
Conchs – excellent sandbed turnover and detritus grazing
Blue-leg Hermits – graze and disturb mats
Trochus Snails – clean hard surfaces and glass
Sand-Sifting Starfish (with caution) – helps in deeper tanks
Notes
⚠️ Notes for Success:
Increase Flow: Especially near the sandbed and dead zones
Cut Back Red/White Light: Reduce photoperiod if needed
Manual Removal: Siphon large mats during water changes
Use a Skimmer or Filter Sock: Improves waste export
Avoid Chemical Quick Fixes: Products like Chemiclean work, but don’t solve the root problem
Pro tip
🧠 Pro Tip:
Cyano is often a symptom, not the disease. The best long-term solution is nutrient balance — not eradication. Pair your clean-up crew with flow upgrades and consistent maintenance for a lasting win.
