The short answer
Most of the time, melting is a transition — not death. Aquarium plants are often grown emersed (above water) at the nursery, and when they go underwater their old leaves die back while the plant grows new submersed leaves suited to your tank. Cryptocoryne are famous for this “crypt melt.” Leave the roots in place and they usually regrow stronger.
Why it happens
The emersed-to-submersed switch forces the plant to rebuild leaves adapted to lower light and dissolved CO2. Old leaves can’t cope and dissolve. Sudden changes in conditions — being moved, a shift in water parameters, temperature or lighting — can trigger the same response even in established crypts. It looks alarming but the energy stays stored in the roots.
How to help them recover
- Be patient and stable: keep light and water parameters steady while the plant adjusts.
- Trim rot: remove fully melted leaves so they don’t pollute the water, but keep the crown and roots.
- Feed the roots: root-feeders like crypts recover faster with nutrients at the roots — see the fertilizer hub and our fertilizer pick. A nutrient-rich substrate helps too.
- Right light: don’t blast a recovering plant — see how much light plants need.
When it’s something else
If leaves keep dying after the plant has settled for over a month, or turn yellow and translucent, it’s likely a deficiency rather than transition melt — read why plants turn yellow. Choosing forgiving species reduces melt in the first place: see the easiest beginner plants and our aquascaping for beginners guide.