java fern

[john fox]

hello everybody,,i have java fern planted with the rizome exposed above the gravel ,the problem is that the leaves are turning black and the new leaves are rotting off the plant .there are new plantlets on some of the leaves,, any suggestions? .also when i plant watersprite they dont root instead they rot below the gravel then float to the top?thanks john fox ps these are in a guppy tank