I recently gave someone some Java Fern that was doing very well in my tank. She tied it down to some wood, where it promptly started to die. Her ph was high due to crushed coral substrate that she has now lowered. It was around 8 - 9. Could that be the reason the java fern died? I thought this plant was indestructable.
The fern has likely not died. It is simply experiencing transplant shock.
I have had ferns die off down to the last leaf of the rhizome. Even the rhizome itself had started to go brown. But the fern came back.
Leave it in the tank. It will recover.