Troubleshoot
Aquarium Plant Root Rot in Aquasoil
Root rot is black, slimy, smelly roots that no longer hold the plant—not just slow growth. Common in compacted aquasoil, deep sand, or buried rhizomes. Fix oxygen in the substrate before you dose more root tabs.
- Root rot
- Black mushy roots
- Anaerobic soil
- Swords & crypts
What you’re seeing
Lift a heavy feeder (sword, crypt, Amazon—see Amazon sword care). Healthy roots are pale/tan and firm. Rot is black, hollow, or falls apart. Leaves may yellow from the crown while stems elsewhere look fine.
| Pattern | Likely driver |
|---|---|
| Black mush + sour smell | Anaerobic pocket |
| Rhizome buried under soil | Anubias/Java fern rot—not a root-tab problem |
| Only one deep corner | No flow through that soil |
| Tiny new leaves, roots still white | Stunt, not rot |
Likely causes (ranked)
Compacted / too-deep substrate
Fine aquasoil packed 10cm+ with no flow goes anaerobic.
Quick test: Soil doesn’t puff when you siphon; H₂S smell.
Buried rhizomes (epiphytes)
Anubias/Java fern rhizomes under soil rot from the inside.
Quick test: Soft rhizome, leaves melting from the base.
Detritus buried in the scape
Uneaten food and mulm in valleys feed bacteria that steal oxygen.
Quick test: Mulm in hardscape pockets; livestock overfed.
Tabs shoved into already-dead soil
More organics into a dead pocket worsens rot.
Quick test: Tabs added last week; smell got worse.
Fix order
-
Step 1
Rescue the plant, not the whole tank
Lift the affected plant. Trim black roots to firm tissue. Rinse. Replant only into loose, oxygenated substrate—or attach epiphytes to wood.
-
Step 2
Open the soil pocket
Siphon mulm. Fluff or thin that corner. Add a little coarser cap if the soil is soup. Don’t recape the entire tank on day one.
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Step 3
Restore gentle flow across the substrate
Aim a filter outlet or small wavemaker so the foreground isn’t dead water.
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Step 4
Hold fertilizer 7–10 days
No new tabs in that pocket until new white root tips appear. Then a single tab under a healthy feeder is enough.
When to escalate
- Whole-tank melt + ammonia → treat water first (ammonia spike).
- Only crypts collapsing after a move → crypt melt.
- No rot but tiny new leaves → stunted growth.
- Sour tank-wide smell → check filter/organics, not just one plant.
Helpful products
Related guides
- Stunted growth — If roots are still white
- Amazon sword care — Heavy feeder
- Crypt melt — Move shock
- CO₂ hub — Stability
FAQ
Is root rot contagious?
It’s usually a local oxygen problem, not a spreading “disease.” Fix that pocket.
Can I use hydrogen peroxide on roots?
A brief outside rinse is optional; don’t dump peroxide into the tank with shrimp.
Do Melaleuca / almond leaves cause rot?
Tannins don’t rot roots. Deep mulm and no flow do.
Should I throw the plant away?
Only if the crown/rhizome is mush. Firm crown + a few white roots can recover.
Are root tabs causing the rot?
Tabs in healthy soil help. Tabs in a dead anaerobic pocket add organics and smell.
Why do only swords rot?
They sit deepest and eat from roots. Stems live higher in the water column.
Aqua Plants Hub Editorial
