Why Anubias Rots When You Bury It in Substrate

Written 2026-11-07

Anubias, Java fern, and Java moss don’t feed through roots buried in the ground — they draw nutrients through a thick rhizome that’s meant to sit on top of the substrate, tied to rock or wood. Bury that rhizome in soil or sand and it slowly rots from lack of oxygen. Running the Water Kiwoogi simulator on a 60cm tank with 4 Anubias nana planted straight into aquarium soil, no rock or driftwood anywhere, and 6 hours of low-light LED a day for 180 days, the rhizome fully rots by day 166. The ammonia it releases knocks the tank out of its settled state — cycling had first finished by day 16, but it doesn’t fully settle again until day 169. Add a single piece of driftwood to the same setup and that relapse never happens.

The rhizome needs something to hold onto

In this simulator’s catalog, Anubias species, Java fern, and Java moss are tagged as epiphytes. An epiphyte loses a little health every hour it sits in a tank with zero rock and zero driftwood anywhere — it can’t anchor its rhizome. Root feeders like swordplants or crypts need a nutrient-rich substrate to thrive, but epiphytes work the opposite way — keep them off the substrate and tie them to rock or wood instead.

We ran 180 days three ways

Everything else stayed fixed — a 60cm standard tank, aquarium soil, a small hang-on-back filter, 6 neon tetras added on day 10, a 25% water change every week — while we changed only the light schedule and whether any rock or wood was in the tank. With the default 8 hours of light, skipping rock and wood caused no relapse at all over 180 days. Cut the light to 6 hours a day with still no rock or wood, and the rhizome fully rots by day 166, pushing nitrite back up slightly on a test kit. The neon tetras weren’t bothered by that small relapse and all 6 survived the full 180 days in every setup — but the plant itself was gone for good.

One piece of rock or wood is enough

The driftwood doesn’t have to be the exact piece you tie the rhizome to — the simulator only checks whether any rock or wood exists anywhere in the tank. Adding one small piece of driftwood kept the rhizome perfectly healthy even on the shorter light schedule. If an Anubias you already planted in substrate is yellowing from the leaf edges or its stem is going soft, it’s safer to lift it out and tie it to the nearest rock or driftwood with thread or fishing line.

The button below runs the tank from this guide — a 60cm standard tank, 6 hours of light, 4 Anubias nana planted straight into soil with no rock or wood. Add a piece of driftwood yourself and watch the rhizome stop rotting.

The numbers in this guide come from the Water Kiwoogi simulator model; real tanks can differ.