From The Aquarium Wiki
What is it?
Cryptocoryne Rot, Crypto Melt or Crypto Rot is when plant leaves in the Cryptocoryne genus appear to 'meltdown' or rot.
Often the edges of the leaves seem to appear as if snails or a fish are eating the edges. As the disease continues the whole leaf or plant may rot away and appear to die off.
What causes this?
This family is sensitive to sudden changes to its environment. So large water changes or adding a lot of fertiliser, sudden changes in lighting levels or temperature can cause this to happen.
Why do the leaves rot?
This family of plants are used to an environment which contains plenty of ammonium and the plant is not evolved to use nitrate as a fuel. So they hold the nitrate internally as stored nutrients within the leaves.
When there is a sudden large water change in the aquarium, a change in light levels or altering fertiliser in the substrate, the plants are shocked due to the sudden need for extra nutrients and so they release their stored nutrients, which includes the unwanted nitrate, and these nitrogen compounds poison the leaves causing the rotting appearance. If allowed to continue it can kill the entire plant.
How to prevent the plant dying?
If you continue to provide enough plant nutrients, CO2, adequate lighting, etc. then whilst the leaves may die off, the plant will regrow new leaves.
- ↑ The book, The Natural Aquarium handbook by Ines Scheurmann. Page 65, ISBN 0-7641-1440-9. Published by Barron's 2nd Ed. 2000AD. 1st issued in 1985. Original German title - Das GU Aquarienbuch.