hi,it is a trident java fern and its got way to big for my tank and is restricting the water flow.You could pull the plant out of the tank and cut the rhizome up and replant in a million bits. It actually looks like part narrow leaved java fern and part trident java fern to me, if so then you could separate the two and grow nice bunches of each. Both are terrific plants. Trident grows smaller and is the divided fronds. Narrow leaf can grow fronds up to about a foot long and is very graceful looking.
You could pull the plant out of the tank, look carefully at it to decide if it can be cut in two and still have a nicely shaped plant, cut those rhizomes then replant.
You could take out the damaged older fronds. I just did that to my Bolbitis and it is half the size it was before. I thought it might be bare in spots treating it like that but apparently the rhizomes are growing every which way and it looks just fine.