Biofilm: that slimy stuff on your driftwood

New driftwood often grows a slimy white or grey film. That’s biofilm — bacteria and microorganisms feeding on sugars and organic matter leaching from the wood. It’s normal, especially in the first few weeks, and usually harmless. Many fish and shrimp graze on it.

When should you worry? If it spreads aggressively, smells foul, or your fish show signs of stress, it’s worth a closer look. Our biofilm guide explains what it is, when to remove it, and how to manage it so your wood stays healthy and your tank stays clean.