White Fungus on Driftwood: Is It Harmful and How to Remove It

What Is the White Stuff on Your Driftwood?

You have just set up a beautiful aquascape with a stunning piece of driftwood as the centrepiece. A few days later, you notice a white, fuzzy, cotton-like growth spreading across its surface. Your first instinct is alarm — it looks like mould, and mould is never a good sign. But before you panic and tear your tank apart, take a breath. What you are looking at is almost certainly biofilm, and it is one of the most common and harmless occurrences in the aquarium hobby.

Despite being widely referred to as “white fungus,” this growth is not actually a true fungus in most cases. It is a bacterial biofilm — a colony of heterotrophic bacteria that are feeding on the organic compounds leaching from the wood. When driftwood is submerged, it releases sugars, tannins, cellulose, and other soluble organic molecules. Bacteria in the water colonise the wood’s surface to consume these nutrients, and the visible white growth is the result of their rapid multiplication.

This process is entirely natural. In rivers and streams, submerged wood is constantly colonised by biofilm. The only reason it surprises aquarists is that we tend to add driftwood to crystal-clear water in an enclosed system, making the growth highly visible.

Is It Harmful to Your Fish?

The short answer is no. This white biofilm is completely harmless to fish, shrimp, snails, and plants. It does not produce toxins, it does not affect water parameters in any meaningful way, and it does not indicate a problem with your water quality or filtration.

In fact, biofilm is a sign of a healthy, biologically active ecosystem. Your aquarium is teeming with beneficial microorganisms, and the bacteria forming this biofilm are simply part of that community. They are not pathogenic — they will not infect your fish or cause disease.

The only legitimate concern is aesthetic. A beautiful piece of Malaysian driftwood or spiderwood covered in white fuzz does not look particularly attractive in a carefully designed aquascape. Fortunately, the growth is temporary, and there are several ways to manage it if the appearance bothers you.

How Long Does It Last?

Biofilm on new driftwood typically follows a predictable timeline:

Days 2-5: First patches of white growth appear, usually starting in crevices and rough areas of the wood
Week 1-2: Growth spreads across more of the wood surface, potentially covering large areas
Week 2-3: Growth begins to diminish as the bacteria exhaust the easily accessible organic compounds
Week 3-6: Biofilm disappears entirely as the wood’s soluble nutrients are depleted

The exact duration depends on several factors. Larger pieces of driftwood with more surface area and mass will sustain biofilm for longer. Softwoods release nutrients faster than dense hardwoods. Warmer water — which is unavoidable in Singapore’s tropical climate — accelerates bacterial growth, so you may see more aggressive biofilm initially, but it will also resolve faster.

Some aquarists report biofilm recurring in waves. This is normal — as bacteria consume the surface-layer nutrients, deeper layers of the wood become exposed, releasing a fresh supply. Each successive wave is typically less dramatic than the last.

Your Natural Cleanup Crew

Here is the silver lining: many common aquarium inhabitants consider biofilm a delicacy.

Shrimp

Neocaridina shrimp (cherry shrimp and their colour variants) and Amano shrimp are voracious biofilm grazers. If you keep shrimp, you may barely notice the white growth at all — they will devour it almost as fast as it appears. In fact, biofilm from new driftwood can serve as an excellent supplementary food source for a shrimp colony.

Snails

Nerite snails, mystery snails, and Malaysian trumpet snails all graze on biofilm. Nerites are particularly efficient and leave clean trails as they work across the wood’s surface.

Otocinclus and Plecos

While these fish are primarily algae eaters, they will also graze on biofilm, particularly when algae is scarce. Bristlenose plecos are especially fond of wood surfaces and will rasp away at both the biofilm and the wood itself.

If you are setting up a new shrimp tank with driftwood, the biofilm phase is actually beneficial. It provides abundant food while the tank matures and natural food sources establish themselves. Many experienced shrimp keepers deliberately add driftwood partly for this reason.

How to Remove It Manually

If the biofilm is unsightly and you do not have (or want) cleanup crew members, you can remove it yourself. Here are effective methods:

Scrubbing

Remove the driftwood from the tank and scrub the affected areas with a clean, unused toothbrush or aquarium-safe brush under running water. Do not use soap or any cleaning products. Replace the wood in the tank. The biofilm may return, but each time you remove it, there is less organic material to sustain regrowth.

Turkey Baster or Syringe

For mild cases or hard-to-remove pieces, use a turkey baster to blast the biofilm off the wood surface while it remains in the tank. The displaced biofilm will float into the water column, where your filter will collect it. Follow up with a small water change if the water becomes cloudy.

Siphoning

During routine water changes, use your gravel vacuum to siphon biofilm directly off the wood surface. This combines removal with water maintenance and is the most practical approach for most aquarists.

Hydrogen Peroxide Spot Treatment

For stubborn patches, you can apply a small amount of 3% hydrogen peroxide (available at any Guardian or Watsons in Singapore) directly to the affected area using a syringe while the wood is outside the tank. Let it sit for five minutes, rinse thoroughly, and return the wood. This is effective but usually unnecessary — the biofilm will go away on its own.

Biofilm vs Actual Fungus: Knowing the Difference

While the vast majority of white growth on aquarium driftwood is harmless bacterial biofilm, it is worth knowing how to distinguish it from genuine fungal growth or other problematic organisms.

Characteristic	Bacterial Biofilm (Harmless)	True Fungus/Mould (Potentially Problematic)
Appearance	White, cottony, fluffy, cloud-like	Often grey, green, or black; may appear slimy
Location	On driftwood and hardscape surfaces	Can appear on driftwood, substrate, or (worryingly) on fish
Smell	None	May produce a foul or musty odour
Duration	Resolves within 1-6 weeks	Persists or worsens over time
Fish reaction	Fish ignore it; shrimp eat it	Fish may avoid the area; does not get eaten
Water impact	None	May cause cloudiness or foul water

The most important distinction is whether the growth appears on the wood or on your fish. White cottony growth on a fish’s body, fins, or mouth is likely a genuine fungal infection (Saprolegnia) and requires immediate treatment. This is a completely different organism from the harmless biofilm on driftwood.

Prevention: Preparing Driftwood Before Use

If you want to minimise biofilm altogether, proper preparation before adding driftwood to your tank makes a significant difference. For a comprehensive guide to selecting and preparing driftwood, see our article on the best driftwood for aquascaping.

Boiling

Boiling driftwood for 1-2 hours accomplishes several things: it sterilises the surface, releases tannins faster (reducing water discolouration), and leaches out many of the soluble organic compounds that bacteria feed on. Smaller pieces can be boiled in a large pot on your kitchen stove. This is the most effective prevention method.

Prolonged Soaking

If the driftwood is too large to boil, soak it in a bucket or container of water for 1-4 weeks, changing the water every few days. This allows the biofilm phase to occur outside the tank. By the time you add the wood, the most readily available nutrients will already be consumed. This method also waterloogs the wood, preventing it from floating.

Scrubbing Before Use

Give new driftwood a thorough scrub with a stiff brush under hot running water before adding it to your tank. This removes loose bark, dirt, and surface organic matter that bacteria can colonise.

Curing with Hydrogen Peroxide

Soak the driftwood in a solution of water and 3% hydrogen peroxide (approximately 1 part peroxide to 3 parts water) for 24 hours. Rinse thoroughly afterward. This kills surface bacteria and oxidises some organic compounds, reducing subsequent biofilm growth.

Even with thorough preparation, some biofilm may still appear. This is because the inner layers of wood continue to release nutrients over time. However, prepared driftwood will produce significantly less biofilm, and what does appear will resolve faster.

When to Actually Worry

While white biofilm on driftwood is harmless, there are a few scenarios where white growth in your aquarium warrants concern:

White growth on fish: Cotton-like patches on a fish’s body, fins, mouth, or eyes are signs of a true fungal infection and require treatment with an antifungal medication.
Foul smell: Healthy biofilm is odourless. If the growth or the wood itself smells rotten, the wood may be decaying internally. Remove it, inspect it, and consider replacing it.
Growth persisting beyond 8 weeks: While biofilm can last several weeks, if white growth continues spreading after two months, the wood may be rotting. Dense hardwoods used in aquascaping should not decompose noticeably for years, but softer woods or improperly cured pieces can break down.
Biofilm on substrate or decorations: A small amount of biofilm on surfaces near the wood is normal. However, extensive white growth across the substrate, on other decorations, or on the glass may indicate excessive organic waste in the water. Test your water parameters and review your feeding and maintenance routine.

Frequently Asked Questions

Will the white biofilm come back after I remove it?

It may return once or twice, but each recurrence is typically less intense. The bacteria are consuming a finite supply of organic material from the wood. Once those nutrients are exhausted, the biofilm stops forming. If you manually remove biofilm, you are also removing the bacteria and some nutrients, which speeds up the overall process. Most aquarists find that biofilm resolves completely within 4-6 weeks.

Does the type of driftwood affect how much biofilm appears?

Yes, significantly. Softwoods and woods with high sap or sugar content tend to produce more biofilm. Spiderwood (also called azalea root) is notorious for heavy biofilm. Malaysian driftwood and Mopani wood, being denser and harder, typically produce less. Cholla wood, popular in shrimp tanks, also produces moderate biofilm. Regardless of wood type, biofilm is always temporary.

Should I remove my driftwood if it develops biofilm?

No, removing and replacing the driftwood is unnecessary. The biofilm is harmless, and removing the wood disrupts your aquascape and stresses your fish. Simply wait for it to resolve naturally, or use one of the manual removal methods described above. If you have shrimp or snails, they will likely handle it for you. The only reason to remove driftwood is if it smells foul or is visibly decomposing.

Can I prevent biofilm by using artificial driftwood instead?

Artificial or resin driftwood will not produce biofilm, since there are no organic compounds for bacteria to feed on. However, many aquarists prefer natural driftwood for its authentic appearance, tannin release (beneficial for many tropical species), and contribution to the biological ecosystem of the tank. The temporary inconvenience of biofilm is a small price to pay for the long-term benefits of real wood.

If you are looking for quality driftwood that has been properly prepared and cured for aquarium use, visit Gensou’s shop at 5 Everton Park. We stock a range of aquascaping hardscape including driftwood, dragon stone, and seiryu stone. Our team can also help you design and build a custom aquarium with professionally prepared materials, so you can skip the trial and error. With over 20 years of aquascaping experience in Singapore, we know how to get your tank looking its best from day one.

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