The short answer
Most ‘melt’ isn’t your plant dying — it’s the plant converting from air-grown to underwater growth. Nurseries grow many aquarium plants emersed (out of water), and those leaves can’t survive submerged, so they dissolve while the plant grows new ones. You can’t fully stop it, but you can keep the plant still, stable and fed so it bounces back fast. Crypts are the classic melters.
Why it happens
Two things trigger melt: the emersed-to-submersed transition just described, and sudden changes — being uprooted, shipped, or dropped into water with very different temperature or chemistry. Cryptocoryne is famous for melting right back to the roots after any disturbance, then regrowing stronger. That’s normal behaviour, not failure.
How to limit it
- Don’t keep moving the plant. Every uproot restarts the clock. Plant once and leave it.
- Keep conditions stable — steady temperature, consistent water changes, no big swings.
- Feed the roots and water. A good fertiliser and, for root-feeders, root tabs help the plant power new growth.
- Trim only the dead. Snip off mushy, fully-browned leaves so they don’t foul the water; leave anything still firm.
When it’s actually rot
Melt should slow and reverse within a few weeks as fresh leaves appear. If leaves keep dissolving with no new growth, or the base is soft and smells foul, that’s rot or a serious deficiency rather than normal melt — check your light and nutrients, and remove any decaying material. For the wider picture see why plants melt and why leaves turn brown.